      Input Description for Program MNDO91.
      Version 3.0 of September 12, 1991, master version.
      Version 3.1 of September 12, 1991, for Cray.
      Version 3.2 of September 12, 1991, for Convex, SNI, and NEC.
      Version 3.3 of September 12, 1991, general Fortran version.
 
      By Walter Thiel, Theoretische Chemie, Universitaet Wuppertal,
      Gaussstrasse 20, D-5600 Wuppertal 1, Germany.
 
      Program for geometry optimization and force constant analysis
      using MNDOC, MNDO, AM1, PM3, MINDO/3 or CNDO/2 wavefunctions.
 
      ******************************************************************
 
      References.
 
      MNDOC     W.Thiel, J.Am.Chem.Soc. 103, 1413, 1420 (1981).
      MNDO      M.J.S.Dewar and W.Thiel, J.Am.Chem.Soc. 99, 4899 (1977).
      AM1       M.J.S.Dewar, E.G.Zoebisch, E.F.Healy and J.J.P.Stewart,
                J.Am.Chem.Soc. 107, 3902 (1985).
      PM3       J.J.P.Stewart, J.Comput.Chem. 10, 209 (1989).
      MINDO/3   R.C.Bingham, M.J.S.Dewar and D.H.Lo, J.Am.Chem.Soc.
                97, 1285 (1975).
      CNDO/2    J.A.Pople and G.A.Segal, J.Chem.Phys. 44, 3289 (1966).
 
      ******************************************************************
 
      There are two modes of input for this program.
 
      - Standard input based on numeric data.
      - MOPAC    input based on keywords and numeric data.
 
      The standard input allows the user to access all options of the
      program. It is fully specified in this input description.
 
      The MOPAC input is provided to allow the use of MOPAC input files.
      The input routines are adapted from program MOPAC(6.0) written by
      J.J.P.Stewart. Most common keywords are recognized by this program
      and converted to options of the standard input. Some keywords are
      not available. In this case the program will print an appropriate
      message and then either stop or ignore the keyword. The treatment
      of all MOPAC(6.0) keywords is fully specified in the last part of
      this input description. The MOPAC input for geometry and symmetry
      (etc) is not described here since it should be the same as in
      MOPAC(6.0), see MOPAC manual for details. Note that a number of
      options in the standard input are not accessible when using the
      MOPAC input.
 
      ******************************************************************
      ******************************************************************
 
      Outline of standard input.
 
      In this section, the standard input is summarized briefly.
      A more detailed description will be given in the next section.
 
      The standard input consists of the following parts.
 
      1.    One card with time limit and general options.
      2.    One card with options for geometry optimization and force
            constant analysis. It is recommended to use the default
            values.
      3.    Cards for the first molecule.
      3.1.  Title card, including special options for the molecule.
      3.2.  Atomic numbers and coordinates, one card per atom.
      3.3.  Option ksym=1. Symmetry conditions.
      3.4.  Option kgeom=1. Definition of a reaction path.
      3.5.  Option iabs(kci)=1.   Data for configuration interaction.
      3.6.  Option iabs(kci)=2-4. Data for perturbation treatment.
      3.7.  Option jop=2-6 and kmass.gt.0. Definition of atomic masses.
      4.    Cards for the following molecules (optional).
            The program allows computations for an arbitrary number
            of molecules to be carried out in a single job. The input
            for each new molecule consists of a new set of cards as
            described under 3.
            The job is terminated if the title card (3.1) for the next
            molecule has 99 in columns 1-2 or if an end-of-file is
            encountered when reading the title card.
 
      Input for continuation jobs (options jop=0-2).
      In order to continue an uncompleted calculation, the input deck
      for the corresponding molecule is resubmitted after setting
      option middle on card 2. The continuation job makes use of the
      information saved on file 4 by the preceding job.
 
      ******************************************************************
 
      Description of standard input.
 
      Columns  Name   Format          Description
 
      1. ***** Time limit card *****************************************
 
         1-5  limit     i5     Time limit in seconds. Default 99999.
                               For negative values limit=-n,
                               redefine limit=99999+n*100000
                               to allow for huge time limits.
         6-10 iop       i5     Choice of semiempirical scf method.
                               =-7 PM3.
                               =-2 AM1.
                               =-1 MNDOC.
                               = 0 MNDO.
                               = 1 MINDO/3.
                               = 2 CNDO/2.
                               Special options for MNDO.
                               =-3 MNDO/H with special treatment of
                                   hydrogen bonds.
                               =-4 MNDO with original (pp,pp) exchange
                                   integrals.
                               =-5 MNDO with original parameters for
                                   Si and S.
                               =-6 MNDO with parameters copied from
                                   MNDO87-MNDO89, very small numerical
                                   deviations from option iop=0 with
                                   parameters copied from MOPAC(6.0).
        11-15 jop       i5     Type of calculation.
                               =-2 Gradient calculation, input geometry.
                               =-1 Standard calculation, input geometry.
                               = 0 Optimization for energy minimum.
                               = 1 Optimization for transition state.
                               = 2 Force constant analysis for input
                                   geometry.
                               = 3 Optimization for energy minimum
                                   and force constant analysis for
                                   optimized geometry.
                               = 4 Optimization for transition state
                                   and force constant analysis for
                                   optimized geometry.
                               = 5 Same as jop=2 initially. However,
                                   use jop=3 if the cartesian gradient
                                   norm turns out to be too large.
                               = 6 Same as jop=2 initially. However,
                                   use jop=4 if the cartesian gradient
                                   norm turns out to be too large.
        16-20 igeom     i5     Type of geometrical coordinates.
                               = 0 Internal coordinates.
                               = 1 Cartesian coordinates.
                               Note that igeom=2 may be used internally
                               in the case of MOPAC input.
        21-25 iform     i5     Type of input for molecular data
                               (see sections 3.2-3.7).
                               = 0 Input in formats described below.
                               = 1 Input in free format.
                               = 2 Treated as iform=1 except for using
                                   a simplified input in free format
                                   for the symmetry data (see 3.3).
                               =-1 Treated as iform=0 except for using
                                   a simplified input in free format
                                   for the symmetry data (see 3.3).
        26-30 imode     i5     Handling of two-electron integrals for
                               MNDO-type wavefunctions (iop.le.0) and
                               choice of subroutine for fock matrix.
                               *** Option for testing and debugging.
                               =-n Integrals are stored in memory as a
                                   matrix - no alternative storage is
                                   considered if memory is too small.
                                   Fock matrix from subroutine fock
                                   if vector length lm6.ge.n, otherwise
                                   fock matrix from subroutine fockx.
                               =-2 Integrals are stored in memory as a
                                   matrix - no alternative storage is
                                   considered if memory is too small.
                                   Fock matrix from subroutine fock.
                               =-1 Integrals are stored in memory as a
                                   matrix - no alternative storage is
                                   considered if memory is too small.
                                   Fock matrix from subroutine fockx.
                               = 0 Integrals are stored in memory as a
                                   matrix by default. However,
                                   if memory is too small, a treatment
                                   using imode=1 is attempted first.
                                   If memory is still too small, the
                                   integrals are handled via imode=10.
                                   Fock matrix from the most appropriate
                                   subroutine as determined internally
                                   - fock or fockx for imode=0,
                                   - fock1/fock2 for imode.gt.0.
                               = 1 Integrals are stored in memory as a
                                   linear array of unique integrals
                                   which requires about half the buffer
                                   of the storage as a matrix.
                                   Stop if memory is too small.
                                   Fock matrix from subroutines fock1/2.
                               = n Disk input/output of two-electron
                                   integrals is enforced using a buffer
                                   of 512*n words (n.gt.1).
                                   Fock matrix from subroutines fock1/2.
                               Option imode=0 is recommended since it
                               will choose the optimum treatment for a
                               given memory size.
         31-35 inout    i5     Storage of data during scf treatment.
                               *** Option for testing and debugging.
                               = 0 All relevant matrices are stored in
                                   memory. If memory is too small, the
                                   program will attempt a treatment
                                   using first inout=1, then inout=2,
                                   and finally inout=3.
                               = 1 The density matrix is stored on disk.
                               = 2 The core hamiltonian matrix, the fock
                                   matrix, and the difference density
                                   matrix are stored on disk.
                               = 3 The core hamiltonian matrix, the fock
                                   matrix, and the difference density
                                   matrix are stored on disk. A less
                                   efficient algorithm is used for
                                   calculating the density matrix
                                   to save additional memory.
                               Option inout=0 is recommended since it
                               will choose the optimum treatment for a
                               given memory size.
                               Note that the memory requirements can be
                               reduced by certain input options, too.
                               - nstart=-1 turns off the extrapolation
                                 in the scf iterations which may be
                                 tolerable in many applications.
                                 The combination nstart=-1, inout=2
                                 requires the same amount of memory as
                                 the combination nstart.ge.0, inout=3.
                               - ifast=2 and idiag=1 enforce the use
                                 of slower diagonalization routines
                                 which is, however, not recommended.
         36-40 iparok   i5     Convention in AM1 and PM3 for elements
                               which have not yet been parametrized
                               but are encountered in the input.
                               = 0 Stop.
                               = 1 Use MNDO parameters, if available.
         41-45 irep     i5     Generation of a new input file nb7.
                               Useful for converting input data to a
                               different format and for saving an
                               optimized geometry for subsequent jobs.
                               = 1 Standard input in standard format.
                               = 2 Suitable for input in free format.
                               = 3 MOPAC input.
                               = 4 Analogous to irep=2, geometry always
                                   generated in cartesian coordinates.
                               = 5 Analogous to irep=3, geometry always
                                   generated in cartesian coordinates.
                               For irep=1-3 the geometry is generated in
                               the same type of coordinates (internal or
                               cartesian) as in the current job.
         46-50 igraph   i5     Generation of output files for further
                               evaluations, in analogy to MOPAC.
                               = 0 Do not write such output files.
                               = 1 Write a graphics file (nb13).
                               = 2 Write a geometry-charge file (nb8)
                                   corresponding to a MOPAC input file,
                                   with the atomic charge given at the
                                   end of the input for each atom.
                                   The geometry is saved in internal
                                   coordinates without symmetry.
                               = 3 Write both output files (nb8,nb13).
         51-55 immok    i5     Molecular mechanics correction for
                               peptides according to MOPAC conventions.
                               = 0 No such correction.
                               = 1 Apply same correction as in MOPAC.
         56-60 ihbond   i5     Geometric criteria for an automatic
                               recognition of hydrogen bonds X...H-Y.
                               Useful in MNDO/H calculations, iop=-3.
                               = 0 Default criteria.
                                   Minimum distance rhxmin=1.1 angstrom.
                                   Maximum distance rhxmax=5.0 angstrom.
                                   Minimum angle    angmin= 90 degree.
                               = 1 Alternative criteria.
                                   Minimum distance rhxmin=1.1 angstrom.
                                   Maximum distance rhxmax=2.5 angstrom.
                                   Minimum angle    angmin=100 degree.
                               = n Input of distance criteria, n.ge.100.
                                   rhxmin = 0.1 angstrom * (n/100)
                                   rhxmax = 0.1 angstrom * mod(n,100)
                                   angmin =  90 degree.
 
 
      2. ***** Card for options ****************************************
 
      Summary of the available options.
 
         1-10 General options for geometry optimizations and for force
              constant calculations.
        11-20 Printing flags.
        21-40 Special options for geometry optimizations.
              For energy minima (jop=0,3,5) all input variables may be
              relevant. For transition states (jop=1,4,6) only some of
              the input variables are defined (iprec,nrst).
        41-50 Special options for line searches.
              For energy minima (jop=0,3,5) all input variables may be
              relevant. For transition states (jop=1,4,6) only some of
              the input variables are defined (lconv,lmaxst).
        51-60 Options for gradient calculations.
        61-70 Options for force constant calculations.
        71-80 Options for the calculation of thermodynamic quantities
              after force constant analysis.
 
         1-2  maxend    i2     Maximum number of scf calculations
                               during each geometry optimization.
                               Default 9999.
                               = 1 Special option for jop=0,1,3,4.
                                   No geometry optimization, only one
                                   scf calculation is carried out for
                                   the input geometry (as with jop=-1).
         3-4  maxlin    i2     Maximum number of scf calculations for
                               each line search in the optimization.
                               Default  4 for lsub=0   (see below).
                               Default 10 for lsub=1,2 (see below).
         5-6  maxrtl    i2     Maximum number of optimization cycles
                               per job. Default 9999.
         7    iscf      i1     Scf convergence criterion for the
                               electronic energy = 10**(-iscf) ev.
                               Default 6 usually.
                               Default 5 for geometry optimizations
                               using variational wavefunctions and
                               normal precision (iprec=1, see below).
                               Recommended minimum 5.
         8    ipl       i1     Scf convergence criterion for the
                               diagonal of the density matrix.
                               Default ipl=iscf usually.
                               Default 3 for geometry optimizations
                               using variational wavefunctions and
                               normal precision (iprec=1, see below).
                               Recommended minimum 3.
                               If the input value of ipl is greater
                               than iscf, the program sets ipl=iscf.
         9-10 middle    i2     Job continuation option for jop=0-2.
                               =-1 Job continuation impossible since
                                   no restart information is saved.
                                   This may be useful for minimizing
                                   disk input/output operations.
                               = 0 Normal job.
                               = 1 Continuation of a previous job
                                   starting with a new cycle and
                                   using information saved on file 4
                                   via middle=0.
                               Additional option for jop=0,1.
                               = 2 Continuation of a previous job
                                   using more stringent convergence
                                   criteria. This option allows the
                                   continuation of jobs which have
                                   converged using less stringent
                                   criteria.
        11-12 iprint    i2     Printing flag for the optimization.
                               =-5 No output.
                               =-1 Small output.
                               = 0 Standard output.
                               = 1 Detailed output.
                                   Required to print the final
                                   interatomic distances for molecules
                                   with 100 or more atoms.
                               = 5 Debug print.
        13-14 kprint    i2     Printing flag for the calculation of
                               force constants.
                               =-5 No output.
                               =-1 Small output.
                               = 0 Standard output.
                               = 1 Detailed output.
                               = 5 Debug print.
        15-16 lprint    i2     Printing flag for the vibrational
                               analysis.
                               =-5 No output.
                               =-2 Minimum output.
                               =-1 Small output.
                               = 0 Standard output.
                               = 1 Detailed output.
                               = 5 Debug print.
        17-18 mprint    i2     Printing flag for the calculation of
                               gradients.
                               =-1 No output.
                               = 0 Standard output.
                               = 1 Detailed output including computed
                                   gradient norms during optimizations.
                                   iprint=1 sets mprint=1 if the input
                                   value is mprint.le.0.
                               = 5 Debug print.
        19-20 jprint    i2     Flag for printing of input data.
                               =-1 No output.
                               = 0 Standard output.
                               = 1 Detailed output.
                               = 2 Detailed output including memory
                                   allocation and rotational data.
                               = 5 Debug print.
                                   Required to print the initial
                                   interatomic distances for molecules
                                   with 100 or more atoms.
        21-24 iprec     i4     Option to increase the precision of
                               the convergence criteria for geometry
                               optimizations.
                               Default 1. Suggested maximum 100.
                               Convergence tests refer to tolend(i).
                               The default values for tolend(i) are
                               divided by iprec to define the actual
                               tolerances used.
                               ***  Conventions for jop=0,3,5.
                               i=1  Test on norm of variables x.
                               i=2  Test on function value f.
                               i=3  Test on gradient components g
                                      or on gradient norm (iconv=-2).
                               i=4  Test on predicted decrease in f.
                               Default values for tolerances.
                               tolend(1)=1.D-04
                               tolend(2)=2.D-03 kcal/mol
                               tolend(3)=1.D+00 kcal/(mol*angstrom)
                               tolend(4)=1.D-03 kcal/mol
                               ***  Conventions for jop=1,4,6.
                               i=1  Test on absolute change of x.
                               i=2  Test on relative change of x.
                               i=3  Test on gradient components g.
                               Default values for the tolerances.
                               tolend(1)=1.D-08
                               tolend(2)=1.D-08
                               tolend(3)=1.D+00 kcal/(mol*angstrom)
        25-26 iconv     i2     Type of convergence criteria for
                               geometry optimizations (jop=0,3,5).
                               =-2 Successful termination if
                                   - test on gnorm satisfied
                               =-1 Successful termination if either
                                   - test on g satisfied
                                   - test on f or x satisfied
                                     for nrepet consecutive cycles
                               = 0 Successful termination if either
                                   - test on g and x satisfied
                                   - test on g and f satisfied
                                   - test on f or  x satisfied
                                     for nrepet consecutive cycles
                                   - test on alpha.p.g satisfied, i.e.
                                     test on predicted decrease in f
                               = 1 Successful termination if either
                                   - test on g and x satisfied
                                   - test on g and f satisfied
                                   - test on f or  x satisfied
                                     for nrepet consecutive cycles
        27-28 ihess     i2     Definition of initial hessian.
                               = 0 Same as ihess=1 except for the
                                   second and following points on a
                                   reaction path where ihess=2 is
                                   assumed.
                               = 1 Initial hessian is estimated from a
                                   finite-difference approximation
                                   using gradient calculations at the
                                   initial point and a neighboring one.
                               = 2 Initial hessian read from file 4.
                               = 3 Initial hessian taken as unit matrix.
                                   Useful for testing purposes only.
        29-30 iup       i2     Update of inverse hessian matrix.
                               = 0 BFGS update.
                               = 1 DFP update.
        31-32 nrepet    i2     Convergence criterion for f and x, see
                               above (iconv). Default 3.
        33-34 nrst      i2     Number of cycles between resetting the
                               hessian matrix to its initial values.
                               Default 999.
                               =-1 Do not reset the hessian matrix
                                   even if the gradient and the search
                                   direction are almost orthogonal.
                                   Define nrst=99999 for internal use.
        35-38 ldrop     i4     A restart in the geometry optimization
                               is carried out if the heat of formation
                               drops by more than ldrop kcal/mole in
                               two consecutive cycles (jop=0,3,5).
                               Default 10.
        39-40 ldell     i2     The geometrical variables in such a
                               restart are changed by 0.001*ldell units
                               (angstrom or radian). Default 10.
        41-42 lsub      i2     Choice of line search routine.
                               = 0 Quadratic search via fstmin.
                               = 1 Quadratic search via locmin.
                               = 2 Cubic search via linmin if gradients
                                   are always available, otherwise
                                   quadratic search via locmin.
        43-44 lalpha    i2     Initial step size for line search.
                               = 0 Taken from preceding cycle (times
                                   pnormlast/pnorm for lsub=1 or 2).
                                   For variational wavefunctions
                                   and lconv.gt.25 (see below), the
                                   program uses lalpha=1 by default.
                               = 1 Use step size alpha=1 initially.
                               = 2 Taken from preceding cycle without
                                   any change.
        45-46 lconv     i2     Convergence criterion for line search.
                               = 0 Convergence if the predicted step
                                   size differs from the previous
                                   step size told by less than
                                   tcrit=0.01*told+0.01
                               = n Multiply default value by n.
                                   For variational wavefunctions and
                                   lsub=0, the program uses lconv=50
                                   by default.
                                   For nonvariational wavefunctions,
                                   the program always uses lconv=1
                                   regardless of the actual input.
        47-48 ltolf     i2     Convergence criterion for line search.
                               = 0 Convergence if the energy drops by
                                   less than 0.5*tolend(2) for two
                                   consecutive points.
                               = n Multiply default value by n.
                                   Negative ltolf values turn off
                                   this convergence criterion.
        49-50 lmaxst    i2     Maximum allowed change of the variables
                               for two consecutive points in the line
                               search.
                               = 0 Use default values of 0.1 angstrom
                                   and 0.1 radian.
                               = n Multiply default values by n.
        51-52 igrad     i2     Method of gradient calculation.
                               = 0 Internal choice depending on the
                                   type of wavefunction.
                               = 1 Slow finite-difference calculation
                                   via full energy evaluations is used
                                   for all types of wavefunctions.
                                   This implies quadratic line searches.
        53-56 lfac      i4     Step size for slow finite-difference
                               calculation of gradient.
                               lfac multiplies the units for the step
                               size of 0.00001 angstrom for distances,
                               0.002 degree for bond angles, and 0.005
                               degree for dihedral angles.
                               Default 100.
        61-62 kpoint    i2     Calculation of the offdiagonal force
                               constants by numerical differentiation
                               of the gradient.
                               = 0 Average from two calculations for
                                   f(i,j) and f(j,i).
                               = 1 One single calculation for f(i,j).
                               For nonvariational wavefunctions with
                               slow finite-difference gradients,
                               kpoint=1 is about twice as fast as
                               kpoint=0, but yields less accurate
                               force constants.
                               For variational wavefunctions with fast
                               gradients, kpoint=0 is always used
                               regardless of the actual input.
        63-64 kmass     i2     Atomic masses used for the vibrational
                               analysis.
                               =-1 Average atomic weight.
                               = 0 Mass of the most abundant isotope.
                               = n In addition to the default case,
                                   n isotopomers are treated which are
                                   defined by input (see 3.7).
                                   A vibrational analysis for isotopic
                                   substitution (defined via kmass=n)
                                   can be done by using a previously
                                   computed force constant matrix from
                                   the restart file (option middle=1).
        65-70 inc       i5     Displacement of cartesian coordinates
                               for force constant calculations in
                               units of 0.00001 au. Default 1000.
        71-72 ntemp     i2     Number of temperatures for calculation
                               of thermodynamic quantities.
                               Default 10. Maximum 25.
                               Default temperatures for ntemp=0 are
                               273.15, 298.15, 300, 400, ... 1000 K
                               regardless of input for ntemp1 and
                               ntemp2.
        73-76 ntemp1    i4     Lowest temperature (in Kelvin).
                               Default 100. Minimum 100.
        77-80 ntemp2    i4     Temperature increment (in Kelvin).
                               Default 100.
 
      3.1 ***** Title card for the molecule ***************************
 
        1-2   kharge    i2     Molecular charge.
                               =99 To terminate the job.
        3-4   imult     i2     Definition of multiplicity.
                               *** Options for RHF calculations.
                               = 0 Closed-shell singlet.
                               = 1 Open-shell singlet with two singly
                                   occupied orbitals. This scf solution
                                   usually corresponds to an excited
                                   singlet state.
                               = 2 Doublet.
                               = 3 Triplet.
                               *** Options for UHF calculations.
                               = 0 Singlet.
                               = 1 Singlet (same as imult=0).
                               = 2 Doublet.
                               = 3 Triplet.
                               = 4 Quartet (etc).
                               *** Note on RHF and UHF calculations.
                               By default, RHF for imult=0 and UHF for
                               imult.gt.0, which may be changed using
                               option iuhf (see below).
                               imult.gt.3 is possible for UHF only.
        5-6   ktrial    i2     Initial density matrix for scf.
                               = 0 Standard diagonal matrix.
                               = 1 Density matrix will be read in from
                                   file 1.
                               = 2 Eigenvectors will be read in from
                                   file 1 to compute density matrix.
                               = 3 RHF density matrix will be read in
                                   from file 1 to form initial alpha
                                   and beta UHF density matrices.
                               = 4 Special option for UHF singlets,
                                   see code in guessp.
                               = 5 Special option for UHF singlets,
                                   see code in guessp.
        7-8   kgeom     i2     Geometry input.
                               = 0 Standard.
                               = 1 Additional input for reaction path.
                               =-1 Program terminates after computing
                                   coordinates and distances (useful
                                   for checking the input data).
        9-10  ipubo     i2     Save scf results on file 1.
                               = 0 Do not save.
                               = 1 Save density matrix.
                               = 2 Save eigenvectors.
                               ipubo is set equal to ktrial by the
                               program for ktrial=1,2 (see above).
       11-12  iuhf      i2     Type of scf calculation.
                               =-1 Always RHF.
                               = 0 RHF for closed-shell systems,
                                   UHF for open-shell systems.
                               = 1 Always UHF.
       13-16  kitscf    i4     Maximum number of scf iterations.
                               Default 50.
       17-18  nprint    i2     Printing flag for scf.
                               =-5 Prints no scf information.
                               =-1 Prints eigenvalues, scf energies,
                                   net charges, and dipole moment.
                               = 0 Prints eigenvalues, eigenvectors,
                                   scf energies, symmetry labels, net
                                   charges, and dipole moment.
                               = 1 Also prints density matrix, and
                                   UHF spin densities.
                               = 2 Also prints scf iterations, core
                                   hamiltonian, and final fock matrix.
                               = 5 Debug printing.
       19     ifast     i1     Fast diagonalizations in scf.
                               = 0 Allowed (whenever possible).
                               = 1 Allowed after initial full
                                   diagonalizations.
                               = 2 Not allowed (for ifast.gt.1).
       20     idiag     i1     Standard diagonalizations in scf.
                               See documentation for details.
                               = 0 In most program versions
                                   treated as idiag=5 (evvrsp).
                               = 1 Using subroutine tdiag for
                                   linear fock matrix (eispack),
                                   calls to tred3,tql2,trbak3.
                               = 2 Using subroutines tred2 and tql2 for
                                   square fock matrix (eispack).
                               = 3 Using subroutine rsm for
                                   square fock matrix (eispack),
                                   calls to tred1,imtqlv,tinvit,trbak1.
                               = 4 Using subroutine hqrii for
                                   square fock matrix.
                               = 5 Using subroutine evvrsp for
                                   square fock matrix (eispack-based),
                                   calls to tred1,eqlrat,einvit,trbak1.
       21-22  ksym      i2     Input of symmetry conditions.
                               = 0 No symmetry conditions.
                               = 1 Read symmetry conditions.
       23-24  numsym    i2     Symmetry number for calculation of
                               thermodynamic quantities.
                               = 0 Automatic determination of the
                                   symmetry number by the program.
                                   This works for most point groups,
                                   but may fail in some complicated
                                   cases (e.g. Dn, Dnd with even n).
                                   Explicit input is then required.
                               = 1 C1,Ci,Cs,C0v.
                               = 2 C2,C2v,C2h,D0h.
                               = 3 C3,C3v,C3h,S6.
                               = 4 C4,C4v,C4h,D2,D2d,D2h.
                               = 5 C5,C5v,C5h.
                               = 6 C6,C6v,C6h,D3,D3d,D3h.
                               = 8 D4,D4d,D4h.
                               =10 D5,D5d,D5h.
                               =12 D6,D6d,D6h,T,Td.
                               =24 Oh.
       25-26  kci       i2     Correlation treatment.
                               = 0 None.
                               = 1 Minimal configuration interaction
                                   involving two RHF mos.
                               = 2 Brillouin-Wigner perturbation method
                                   with one main configuration. BWEN.
                               = 3 Brillouin-Wigner perturbation method
                                   with two main configurations. BWEN1.
                               = 4 Brillouin-Wigner perturbation method
                                   with two main configurations. BWEN2.
                               For negative kci, geometry optimizations
                               are done at the scf level, followed by a
                               single correlated calculation at the
                               final geometry, according to iabs(kci).
       27-28  nstart    i2     First scf extrapolation in cycle nstart.
                               =-1 No extrapolation in scf treatment.
                                   The program also sets nstart=-1 in
                                   the case nstart.gt.kitscf.
                               = 0 Use nstart=4 by default.
       29-30  nstep     i2     Following scf extrapolations every nstep
                               cycles. Default 4.
       31-78  ktitle    a      Title for the molecule.
 
      3.2 ***** Molecular geometry ***** One card per atom *************
 
      The input in this section is either formatted (option iform=0)
      or in free format (option iform.gt.0). The column numbers and the
      formats given below refer to the option iform=0.
 
      Depending on the value of variable igeom (see first card), the
      geometry may be defined in internal coordinates or in cartesian
      coordinates. The geometrical data are stored in a(j,i) where i
      is the number of the atom and j the type of coordinate as given
      in the following table.
      j   internal coordinate   cartesian coordinate
      1   bond length           x-coordinate
      2   bond angle            y-coordinate
      3   dihedral angle        z-coordinate
 
      In the case of internal coordinates, each atom i is defined with
      respect to three reference atoms na(i),nb(i),nc(i) as follows.
      1   bond length      i-na(i)
      2   bond angle       i-na(i)-nb(i)
      3   dihedral angle   i-na(i)-nb(i)-nc(i)
      For the first three atoms, there are special conventions.
      Atom 1 is put into the origin, no geometry input needed.
      Atom 2 is put on the positive x-axis, bond length 2-1 as input.
      Atom 3 is put into the xy-plane with positive y-coordinate,
      bond length 3-na(3) and bond angle 3-na(3)-nb(3) as input,
      with default values na(3)=2 and nb(3)=1.
 
      In the case of cartesian coordinates, reference atoms are not
      needed for the definition of the geometry. They must be omitted
      when using input in free format (iform.gt.0).
 
      Cartesian coordinates and bond lengths are given in angstrom,
      and angles in degree.
 
        1-2   nat(i)    i2    Atomic number of atom (i).
                              =99 for a dummy atom which only assists
                                  in the definition of the geometry.
                              = 0 to end input of geometry.
       11-20  a(1,i)   f10.5  First coordinate.
       23-24  la        i2    Optimization of first coordinate.
                              = 0 a(1,i) is not optimized.
                              = 1 a(1,i) is optimized.
       31-40  a(2,i)   f10.5  Second coordinate.
       43-44  lb        i2    Optimization of second coordinate.
                              = 0 a(2,i) is not optimized.
                              = 1 a(2,i) is optimized.
       51-60  a(3,i)   f10.5  Third coordinate.
       63-64  lc        i2    Optimization of third coordinate.
                              = 0 a(3,i) is not optimized.
                              = 1 a(3,i) is optimized.
       71-72  na(i)     i2    Number of first  reference atom.
       73-74  nb(i)     i2    Number of second reference atom.
       75-76  nc(i)     i2    Number of third  reference atom.
 
                              End input of geometry by nat(i).le.0.
                              In the case of formatted input a blank
                              card may be used for this purpose.
 
      3.3 ***** Symmetry data ***** ksym=1 *****************************
 
      The input in this section is either formatted (option iform=0)
      or in free format (option iform=1). The column numbers and the
      formats given below refer to the option iform=0.
 
      A simplified input in free format (options iform=-1, iform=2)
      allows to specify only a single dependent atom, i.e. L3(1),
      see description below.
 
      Symmetry may be imposed by specifying a reference atom L1, a
      symmetry relation number L2, and up to 10 dependent atoms L3.
      The symmetry relation number L2 defines the coordinates
      a(j,L3) of the dependent atoms in terms of the coordinate
      a(k,L1) of the reference atom.
 
      The type of the coordinates involved is defined implicitly
      by the symmetry relation number L2 (see below). Notation:
      j   internal coordinate   cartesian coordinate
      1   bond length           x-coordinate
      2   bond angle            y-coordinate
      3   dihedral angle        z-coordinate
 
      There are 33 predefined symmetry relations available, for L2
      values between 1 and 33, which are listed below.
 
        1-2   L1         i2   Number of the reference atom.
        3-5   L2         i3   Number of symmetry relation.
                              = 1 implies a(1,L3)= a(1,L1)
                              = 2 implies a(2,L3)= a(2,L1)
                              = 3 implies a(3,L3)= a(3,L1)
                              = 4 implies a(3,L3)=  90-a(3,L1)
                              = 5 implies a(3,L3)=  90+a(3,L1)
                              = 6 implies a(3,L3)= 120-a(3,L1)
                              = 7 implies a(3,L3)= 120+a(3,L1)
                              = 8 implies a(3,L3)= 180-a(3,L1)
                              = 9 implies a(3,L3)= 180+a(3,L1)
                              =10 implies a(3,L3)= 240-a(3,L1)
                              =11 implies a(3,L3)= 240+a(3,L1)
                              =12 implies a(3,L3)= 270-a(3,L1)
                              =13 implies a(3,L3)= 270+a(3,L1)
                              =14 implies a(3,L3)=-a(3,L1)
                              =15 implies a(1,L3)= a(1,L1)*0.5
                              =16 implies a(2,L3)= a(2,L1)*0.5
                              =17 implies a(2,L3)= 180-a(2,L1)
                              =18 implies a(1,L3)= a(1,L1)*depfac
                              =19 implies a(1,L3)= a(1,L1)*0.763932022
                              =20 implies a(1,L3)= a(1,L1)/sqrt(2.0)
                              =21 implies a(1,L3)=-a(1,L1)
                              =22 implies a(2,L3)=-a(2,L1)
                              =23 implies a(3,L3)=-a(3,L1)
                              =24 implies a(2,L3)= a(1,L1)
                              =25 implies a(1,L3)= a(2,L1)
                              =26 implies a(3,L3)= a(1,L1)
                              =27 implies a(1,L3)= a(3,L1)
                              =28 implies a(3,L3)= a(2,L1)
                              =29 implies a(2,L3)= a(3,L1)
                              =30 implies a(2,L3)= 180+a(2,L1)
                              =31 implies a(3,L3)= a(3,L1)*0.5
                              =32 implies a(3,L3)= a(3,L1)*2.0
                              =33 implies a(3,L3)= 120-a(3,L1)*2.0
                              The most useful symmetry relations are
                              L2=1,2,3,14. The relations L2=4-13 are
                              used only for internal coordinates, and
                              L2=24-29 only for cartesian coordinates.
       20-22  L3(1)      i3   Number of dependent atom.
       25-27  L3(2)      i3   Number of dependent atom.
       30-32  L3(3)      i3   Number of dependent atom.
       35-37  L3(4)      i3   Number of dependent atom.
       40-42  L3(5)      i3   Number of dependent atom.
       45-47  L3(6)      i3   Number of dependent atom.
       50-52  L3(7)      i3   Number of dependent atom.
       55-57  L3(8)      i3   Number of dependent atom.
       60-62  L3(9)      i3   Number of dependent atom.
       65-67  L3(10)     i3   Number of dependent atom.
                              For definition of n dependent atoms,
                              L3(1) up to L3(n) must be nonzero.
                              When using options iform=2 or iform=-1
                              only L3(1) is read in free format.
 
                              End input of symmetry by L1.le.0.
                              In the case of formatted input a blank
                              card may be used for this purpose.
 
      The symmetry relation L2=18 requires additional input of the
      factor depfac, immediately after the line containing L2=18.
      The input is in free format for iform.ne.0.
 
       1-10   depfac  f10.5   Factor to be used with L2=18 (see above).
                              Only one such factor can be defined for
                              a given molecule.
 
      3.4 ***** Reaction path ***** kgeom=1 ****************************
 
      The input in this section is either formatted (option iform=0)
      or in free format (option iform=1). The column numbers and the
      formats given below refer to the option iform=0.
 
      *** First card ***
 
        1-5   lr1        i5   Atom on which the reaction coordinate
                              is located.
        6-10  lr2        i5   Type of reaction coordinate.
                              lr2  internal coord   cartesian coord
                              1    bond length      x-coordinate
                              2    bond angle       y-coordinate
                              3    dihedral angle   z-coordinate
       11-15  npoint     i5   Number of points on the reaction path,
                              in addition to the initial point.
                              Maximum 200.
 
      *** Second card ***
 
        1-80  rc(i)   8f10.5  Npoint values for the reaction coordinate.
                              Use more than one card for npoint.gt.8.
 
      3.5 ***** Configuration interaction ***** iabs(kci)=1 ************
 
      The input in this section is either formatted (option iform=0)
      or in free format (option iform=1). The column numbers and the
      formats given below refer to the option iform=0.
 
        1-5   k         i5    Number of mo involved in CI (see below).
        6-10  l         i5    Number of mo involved in CI (see below).
       11-15  nc        i5    Number of configurations involved in CI.
                              Default values are defined below.
                              Explicit input is possible only for
                              singlets with imult=0 (see below).
       16-20  lroot     i5    CI state whose geometry is optimized.
                              Default 1.
 
      Three types of minimal configuration interaction are possible
      which, in each case, involve two RHF mos k and l.
 
      imult=0, singlet, closed-shell RHF mos, 2*2 CI or 3*3 CI.
      k is an   occupied mo (default homo).
      l is an unoccupied mo (default lumo).
      Default. nc=3, 3*3 CI with configurations kk,ll,kl.
      Input of nc=2 leads to a 2*2 CI with configurations kk,ll.
 
      imult=1, singlet, open-shell half-electron RHF mos, 3*3 CI.
      k and l are the two singly occupied RHF mos.
      nc=3, 3*3 CI with configurations kk,kl,ll.
      These default values cannot be changed via input.
 
      imult=2, doublet, open-shell half-electron RHF mos, 2*2 CI.
      Case a. k singly occupied mo, l unoccupied mo (default lumo).
      Case b. l singly occupied mo, k   occupied mo (default homo-1).
      Case a  is the default case.
 
      3.6 ***** Perturbation treatment ***** iabs(kci)=2-4 *************
 
      The input in this section is either formatted (option iform=0)
      or in free format (option iform=1). The column numbers and the
      formats given below refer to the option iform=0.
 
      *** First card ***
 
        1-4   ici1      i4    Total number of occupied orbitals to be
                              included in the perturbation treatment.
                              Default all, up to a maximum of 20.
                              Higher ici1 values (ici1.gt.20) are not
                              selected by default and must be read in.
        5-8   ici2      i4    Total number of unoccupied orbitals to be
                              included in the perturbation treatment.
                              Default all, up to a maximum of 20.
                              Higher ici2 values (ici2.gt.20) are not
                              selected by default and must be read in.
        9-12  ioutci    i4    Printing flag.
                              =-5 No output.
                              = 0 Standard output.
                              = 4 Debug print.
       13-16  movo      i4    Definition of orbitals involved in the
                              perturbation treatment. Default 0.
                              = 0 Use ici1 highest  occupied orbitals
                                  and ici2 lowest unoccupied orbitals.
                              = 1 Read orbital numbers on extra cards.
       17-20  mpert     i4    Type of perturbation treatment. Default 0.
                              = 0 BWEN treatment (see below).
                              = 1 Select treatment on extra card.
 
      *** Second card (omit if movo.eq.0) ***
 
        1-80  imoci(i) 20i4   Numbers of occupied orbitals involved in
             (i=1,ici1)       the perturbation treatment. The numbering
                              refers to the scf output. Use more than
                              one card for input, if necessary.
 
      *** Third  card (omit if movo.eq.0) ***
 
        1-80  imoci(i) 20i4   Numbers of unoccupied orbitals involved in
             (i=ici1+1,       the perturbation treatment. The numbering
              ici1+ici2)      refers to the scf output. Use more than
                              one card for input, if necessary.
 
      *** Fourth card (omit if mpert.eq.0) ***
 
        1-16  ipert(i) 4i4    Definition of perturbation treatment.
                              i=1 RSMP, i=2 RSEN, i=3 BWMP, i=4 BWEN.
                              RS Rayleigh-Schroedinger treatment.
                              BW Brillouin-Wigner treatment.
                              MP Moller-Plesset denominators.
                              EN Epstein-Nesbet denominators.
                              For nonzero ipert(i), a perturbation cal-
                              culation is carried out, according to i.
                              For positive ipert(i), the perturbation
                              correction is added to the total energy.
                              Default. BWEN treatment, only ipert(4)=1.
 
      3.7 ***** Definition of masses ***** jop=2-6 and kmass.gt.0 ******
 
      The input in this section is either formatted (option iform=0)
      or in free format (option iform=1). The column numbers and the
      formats given below refer to the option iform=0.
 
        1-80  imass(i) 20i4   Mass of atom i in vibrational analysis.
                              = 0 Use mass of principal isotope.
                              = m Use mass of isotope with m nucleons.
                              The following isotopes are available.
                              H-2,H-3,Li-6,B-10,C-13,N-15,O-17,O-18,
                              Mg-25,Mg-26,Si-29,Si-30,S-33,S-34,Cl-37.
                              If imass(i) does not correspond to one
                              of these isotopes, the default mass of
                              the principal isotope is taken.
 
                              Use more than one card, if necessary.
 
      For kmass=n.gt.1, there are n such definitions which are read
      to define n isotopomers.
 
      4. ***** Input for the next molecule *****************************
 
      At this point, the next molecule can be read in starting with the
      title card. The job is terminated if kharge=99 is read in columns
      1-2 of the title card or if an end-of-file is encountered.
 
      ******************************************************************
      ******************************************************************
 
      Description of MOPAC input keywords in this program.
 
      The first line of a MOPAC input file contains the keywords which
      control the calculation. In the following we give a complete list
      of the keywords in MOPAC(6.0) and specify the response of this
      program when encountering a given keyword. This specification
      includes the following information.
 
      Availability     yes      Keyword fully implemented.
                       no       Keyword not implemented.
                       partly   Similar option is available.
      Basic action     okay     Use equivalent standard input option.
                       stop     Stop the calculation.
                       ignore   Continue and ignore the keyword.
                       similar  Use a similar standard input option.
      Translation      iop=..   Definition of standard input options
                                used to implement the keyword.
                                See detailed descriptions above.
 
      Additional remarks are usually given for each keyword. The list
      of keywords below is ordered alphabetically.
 
      Keyword     Avail-   Basic    Trans-      Remarks
                  ability  action   lation
 
      &           yes      okay                 next line has keywords
      +           yes      okay                 extra line of keywords
      1electron   partly   similar  nprint= 2   print final hcore matrix
      0scf        yes      okay     kgeom =-1   for checking input data
      1scf        yes      okay     jop   =-1   do one scf and stop
      aider       no       stop                 read ab initio gradients
      aigin       yes      okay                 read ab initio geometry
                                                as Gaussian Z-matrix
      aigout      no       stop                 print ab initio geometry
                                                in Gaussian format
      am1         yes      okay     iop   =-2   use AM1 method
      analyt      no       stop                 analytical gradients
      author      yes      okay                 print author of program
      bar=n.n     no       stop                 option for *saddle*
      biradical   yes      okay     imult = 1   half-electron 3*3 CI
                                    kci   = 1   for singlet states
      bonds       partly   similar  nprint= 1   print final p matrix
      c.i.=n      partly   okay     kci   = 1   if n=2, minimal CI
                           stop                 if n.ne.2
      camp        no       stop                 use camp-king method
                                                for scf convergence
      charge=n    yes      okay     kharge= n   molecular charge
      compfg      no       ignore               printing in compfg
      connolly    no       stop                 option for *esp*
      cycles=n    yes      okay     maxrtl= n   no. of cycles in nllsq
      dcart       no       ignore               printing in dcart
      debug       no       ignore               special debug output
      debugpulay  no       stop                 option for *pulay*
      denout      yes      okay     ipubo = 1   save p matrix on file 1
      density     partly   similar  nprint= 1   print final p matrix
      dep         no       stop                 generate new code for
                                                blockdata section
      depvar=n    yes      okay     depfac= n   special symmetry input
                                                for relation L2=18
      deriv       no       ignore               printing in deriv
      dforce      yes      okay     jop   = 5   do force constants
                                    jop   = 6   if *nllsq* is specified
                                    lprint= 1   printing in force
      dfp         yes      okay     iup   = 1   DFP update in flepo
      dipole      no       stop                 fit ESP to total dipole
      dipx        no       stop                 fit ESP to dipole (in x)
      dipy        no       stop                 fit ESP to dipole (in y)
      dipz        no       stop                 fit ESP to dipole (in z)
      dmax=n.nn   no       stop                 option for *ef*
      doublet     yes      okay     imult = 2   doublet, RHF or UHF
      drc         no       stop                 dynamic reaction coord.
      dump=n      no       ignore               restart file is saved
                                                automatically
      echo        yes      okay                 echo input data to user
      ef          no       stop                 eigenvector following
      eiginv      no       stop                 option for *ef*
      eigs        no       ignore               printing in iter
      enpart      no       stop                 energy partitioning
      esp         no       stop                 electrostatic potential
      esprst      no       stop                 option for *esp*
      esr         no       stop                 unpaired spin density
                                                RHF - not available
                                                UHF - *esr* not needed
      excited     yes      okay     lroot = 2   optimize geometry for
                                    kci   = 1   second-lowest singlet
                                    imult = 1   CI state
      external    no       stop                 read external parameters
      fill=n      no       stop                 force population of mos
      flepo       partly   similar  iprint= 1   printing in flepo
      fmat        partly   similar  kprint= 1   printing in fmat
      fock        partly   similar  nprint= 2   print final fock matrix
      force       yes      okay     jop   = 5   do force constants
                                    jop   = 6   if *nllsq* is specified
      fulscf      yes      okay     igrad = 1   full finite-difference
                                                gradients always
      geo-ok      no       ignore               check on distances
      gnorm=n.n   yes      okay     iconv =-2   convergence criterion
                                    iprec =-10  on gradient norm
      gradients   yes      okay     jop   =-2   do one scf + gradients
      graph       yes      okay     igraph= 1   save file for graphics
      hcore       no       ignore               printing in hcore
      hess=n      no       stop                 option for *ef*
      h-prio      no       stop                 option for *drc*
      hyperf      no       stop                 hyperfine couplings
      interp      no       stop                 option for *camp*,*king*
      irc         no       stop                 intrinsic reaction coord
      isotope     yes      okay     middle= 0   save force constants
                                                on file for restart
      iter        no       ignore               printing in iter
      itry=n      yes      okay     kitscf= n   no. of scf iterations
      iupd=n      no       stop                 option for *ef*
      k=(n.nn,n)  no       stop                 brillouin zone structure
      kinetic     no       stop                 option for *drc*
      king        no       stop                 use camp-king method
                                                for scf convergence
      large       no       ignore               printing option
      let         yes      okay                 override safety checks
                                    jop   = 2   for force constants and
                                                for input gradient norm
      linmin      partly   similar  iprint= 1   printing in linmin
      localize    no       stop                 find localized mos
      locmin      partly   similar  iprint= 1   same as *linmin*
      mindo/3     yes      okay     iop   = 1   use MINDO/3 method
      meci        no       ignore               printing in CI treatment
      micros      no       stop                 special CI input
      mmok        yes      okay                 mm correction, CONH
      mndo        yes      okay     iop   = 0   use MNDO method
      mode        no       stop                 option for *ef*
      moldat      no       ignore               printing in input part
      ms=n        no       stop                 spin component in CI
      mullik      no       ignore               mulliken populations
      nllsq       yes      okay     jop   = 1   minimize gradient norm
                                    jop   = 4   when used with *optfor*
                                    jop   = 6   when used with *force*
      noanci      no       ignore               non-analytical CI derivs
      nodiis      no       ignore               no DIIS in optimization
      nointer     no       ignore               do not print distances
      nolog       no       ignore               no entry in LOG file
      nomm        yes      okay                 no mm correction, CONH
      nonr        no       stop                 option for *ef*
      nothiel     yes      okay     lsub  = 1   no FSTMIN line search
      noxyz       no       ignore               do not print x,y,z coord
      nsurf       no       stop                 option for *esp*
      oldens      yes      okay     ktrial= 1   read initial p matrix
      oldgeo      yes      okay                 keep previous geometry
      opci        no       ignore               printing in CI part
      open        partly   okay     imult =1-3  RHF open-shell input
                                                for ielec=ilevel=1-2,
                  partly   stop                 other more complicated
                                                RHF open-shell input
      oride       no       stop                 option for *ef*
      parasok     yes      okay     iparok= 1   use some MNDO parameters
                                                in AM1 or PM3
      pi          no       ignore               sigma/pi analysis for p
      pl          partly   similar  nprint= 2   print pl in iter
      pm3         yes      okay     iop   =-7   use PM3 method
      point=n     yes      okay                 number of points on path
      point1=n    no       stop                 number of points on grid
      point2=n    no       stop                 number of points on grid
      polar       no       stop                 polarizabilities
      potwrt      no       stop                 option for *esp*
      powsq       no       stop                 print option for *sigma*
      precise     partly   similar  iprec =100  increase precision of
                                                various criteria
      pulay       no       stop                 use pulay method for
                                                scf convergence
      quartet     partly   similar  imult = 4   quartet, UHF only
      quintet     partly   similar  imult = 5   quintet, UHF only
      recalc=n    no       stop                 option for *ef*
      restart     yes      okay     middle= 1   continue previous job
      root=n      partly   okay     lroot = n   if n.le.3, minimal CI
                           stop                 if n.gt.3
      rot=n       yes      okay     numsym= n   symmetry number
      s1978       yes      okay     iop   =-5   use 1978 S parameters
      saddle      no       stop                 special ts search
      scale=n.nn  no       stop                 option for *esp*
      scfcrt=.n   yes      okay     iscf  = n   scf criterion on energy
      scincr=n.nn no       stop                 option for *esp*
      search      partly   similar  iprint= 1   same as *linmin*
      setup       yes      okay                 read keywords from file
      sextet      partly   similar  imult = 6   sextet, UHF only
      shift=n     no       stop                 level shifting in scf
      si1978      yes      okay     iop   =-5   use 1978 Si parameters
      sigma       no       stop                 use *nllsq* instead
      singlet     yes      okay     imult = 0   closed-shell singlet
      slope       no       stop                 option for *esp*
      spin        partly   similar  nprint= 1   print UHF spin matrix
      step=n.nn   yes      okay                 step size in path
      step1=n     no       stop                 two-dimensional grid
      step2=n     no       stop                 two-dimensional grid
      sto3g       no       stop                 option for *esp*
      symavg      no       stop                 option for *esp*
      symmetry    yes      okay     ksym  = 1   impose symmetry
      t=n         yes      okay     limit = n   time limit for job
      thermo      yes      okay     ntemp = 0   thermodynamics after
                                                force calculation at
                                                default temperatures
      thermo(nnn) yes      okay     ntemp1= n   *thermo* at temperatures
                                    ntemp2= k   specified by (nnn) =
                                                (n) or (n,m) or (n,m,k)
      times       no       ignore               print internal timings
      t-prio      no       stop                 option for *drc*
      trans       no       ignore               not needed, only real
                                                vibrational modes are
                                                included by default
      triplet     yes      okay     imult = 3   triplet, RHF or UHF
      ts          no       stop                 locate transition state
                                                by *ef* procedure
      uhf         yes      okay     iuhf  = 1   do UHF calculation
      vectors     partly   similar  nprint= 0   print final eigenvectors
      velo        no       stop                 option for *drc*
      williams    no       stop                 option for *esp*
      x-prio      no       stop                 option for *drc*
      xyz         yes      okay                 use x,y,z coordinates
                                                with MOPAC input in
                                                internal coordinates
 
      Further information on the treatment of the MOPAC keywords may be
      obtained from subroutine wrtkey which governs the response of this
      program to any given MOPAC keyword. It should also be noted that
      the default values for certain variables differ from the standard
      values (defined for the standard input) when using MOPAC input,
      in order to stay as close as possible to the conventions used in
      MOPAC(6.0), e.g. limit=3600, ipl=4, iuhf=-1, kitscf=200, and
      nprint=-1 (see subroutine wrtkey). Note, in particular, that
      odd-electron systems are treated as doublets (imult=2) by default
      when using MOPAC input, whereas imult=2 must be specified when
      using standard input (to avoid an input error). Finally, a few
      additional keywords have been defined which are listed below.
 
      cndo/2      iop= 2   use CNDO/2 method
      mndoc       iop=-1   use MNDOC  method with BWEN (kci=2)
      mndoh       iop=-3   use MNDO/H method for hydrogen bonds
      optfor      jop= 3   optimization followed by force calculation
                  jop= 4   when used with *nllsq*, ts search followed
                           by force calculation
      geosave=n   irep=n   generate new input on file nb7, see irep
 
 
 
      ******************************************************************
      ******************************************************************
 
      File dictionary.
 
      1    Sequential disk file.
           Used for input  of density matrix, if ktrial=1.
           Used for input  of eigenvectors  , if ktrial=2.
           Used for output of density matrix, if ipubo =1.
           Used for output of eigenvectors  , if ipubo =2.
           Used to store density matrices during job, if inout.gt.0.
      2    Sequential disk file.
           Used to store the two-electron ao integrals in scf  section.
           Used to store the two-electron mo integrals in pert section.
      3    Sequential disk file.
           Used to store the h,f matrices in scf section, if inout.gt.1.
           Used to store ordered ao integrals in pert section.
      4    Sequential disk file.
           Used to store information for job continuation in geometry
           optimizations and force constant calculations.
           This file must be permanent if job continuation is desired.
      5    Input  file.
      6    Output file.
      7    Sequential disk file.
           Used for generating a new input file which contains either
           the current input geometry in a different format or
           the final optimized geometry from the current job.
      8    Sequential disk file.
           Used for generating an output file which contains the
           final geometry of the current job and the atomic charges.
      13   Sequential disk file.
           Used to store data for graphics evaluation according to
           MOPAC conventions.
 
      File 1 will be used only if the corresponding input/output options
      are read in (see above) or if the available buffer is insufficient
      (inout.gt.0, as determined by the program).
      Files 2 and 3 will likewise be used only if the available buffer
      is insufficient (as determined by the program).
      File 4 will always be used in geometry optimizations and force
      constant calculations (for middle.ge.0).
      File 7 will be used only if requested by input option irep.
      File 8 will be used only if requested by input option igraph.
      File 13 will be used only if requested by input option igraph.
 
      The numbers of files 1-7 can be redefined in the main program
      by changing the variables nb1-nb7.
      The number of file 8 can be redefined in subroutine graph2,
      see variable nb8.
      The number of file 13 can be redefined in subroutine graph,
      see variable nb13.
 
      ******************************************************************
 
