input_description -distribution {Quantum Espresso} -package PWscf -program pp.x {

    toc {}

    intro {
        @b {Purpose of pp.x:} data analysis and plotting.
        
        The code performs two steps:
	
        (1) reads the output produced by @b pw.x, extracts and calculates
	    the desired quantity/quantities (rho, V, ...)
	
        (2) writes the desired quantity to file in a suitable format for
            various types of plotting and various plotting programs

        The input data of this program is read from standard input
        or from file and has the following format:

        NAMELIST @b &INPUTPP
           containing the variables for step (1), followed by

        NAMELIST @b &PLOT
           containing the variables for step (2)

        The two steps can be performed independently. In order to perform
        only step (2), leave namelist @b &INPUTPP blank. In order to perform
        only step (1), do not specify namelist @b &PLOT

        Intermediate results from step 1 can be saved to disk (see
        variable @ref filplot in @b &INPUTPP) and later read in step 2.
        Since the file with intermediate results is formatted, it
        can be safely transferred to a different machine. This 
        also allows plotting of a linear combination (for instance,
        charge differences) by saving two intermediate files and
        combining them (see variables @ref weight and @ref filepp in @b &PLOT)

        All output quantities are in ATOMIC (RYDBERG) UNITS unless
        otherwise explicitly specified.
        All charge densities integrate to the NUMBER of electrons
        not to the total charge.
        All potentials have the dimension of an energy (e*V, not V).
    }

    namelist INPUTPP {

        var prefix -type CHARACTER {
            info { 
                prefix of files saved by program pw.x 
            }
        }
        
        var outdir -type CHARACTER {
            info {
                directory containing the input data, i.e. the same as in pw.x
            }
            default {
                value of the @tt ESPRESSO_TMPDIR environment variable if set;
                current directory ('./') otherwise
            }
        }
        
        var filplot -type CHARACTER {
            info { 
                file "filplot" contains the quantity selected by plot_num 
                (can be saved for further processing)
            }
        }
        
        var plot_num -type INTEGER {
            info { 
                Selects what to save in filplot:

                   0  = electron (pseudo-)charge density
		   
                   1  = total potential V_bare + V_H + V_xc
		   
                   2  = local ionic potential V_bare
		   
                   3  = local density of states at specific energy or grid of energies
                        (number of states per volume, in bohr^3, per energy unit, in Ry) 
		   
                   4  = local density of electronic entropy
		   
                   5  = STM images
                        Tersoff and Hamann, PRB 31, 805 (1985)
		   
                   6  = spin polarization (rho(up)-rho(down))
		   
                   7  = contribution of selected wavefunction(s) to the
                        (pseudo-)charge density. For norm-conserving PPs,
                        |psi|^2 (psi=selected wavefunction). Noncollinear case:
                        contribution of the given state to the charge or
                        to the magnetization along the direction indicated
                        by spin_component (0 = charge, 1 = x, 2 = y, 3 = z )
		   
                   8  = electron localization function (ELF)
		   
                   9  = charge density minus superposition of atomic densities
		   
                   10 = integrated local density of states (ILDOS)
                        from @ref emin to @ref emax (emin, emax in eV)
                        if @ref emax is not specified, @ref emax=E_fermi
		   
                   11 = the V_bare + V_H potential
		   
                   12 = the sawtooth electric field potential (if present)
		   
                   13 = the noncollinear magnetization.
		   
                   17 = all-electron valence charge density
                        can be performed for PAW calculations only 
                        requires a very dense real-space grid!
		   
                   18 = The exchange and correlation magnetic field in the noncollinear case
		   
                   19 = Reduced density gradient 
                        ( J. Chem. Theory Comput. 7, 625 (2011), doi:10.1021/ct100641a )
                        Set the isosurface between 0.3 and 0.6 to plot the 
                        non-covalent interactions (see also plot_num = 20)
		   
                   20 = Product of the electron density (charge) and the second 
                        eigenvalue of the electron-density Hessian matrix;
                        used to colorize the RDG plot (plot_num = 19)
		   
                   21 = all-electron charge density (valence+core).
                        For PAW calculations only; requires a very dense real-space grid. 

                   22 = kinetic energy density (for meta-GGA and XDM only)
            }
        }

        choose {
            when -test "plot_num=0" {
                label {
                    Options for total charge (plot_num=0): 
                }
                
                var spin_component -type INTEGER {
                    default 0 
                    info {
                        0 = total charge (default value),
                        1 = spin up charge,
                        2 = spin down charge.
                    }
                }
            }
            
            elsewhen -test "plot_num=1" {
                label {
                    Options for total potential (plot_num=1): 
                }
                
                var spin_component -type INTEGER {
                    default 0 
                    info {
                        0 = spin averaged potential (default value),
                        1 = spin up potential,
                        2 = spin down potential.
                    }
                }
            }

            elsewhen -test "plot_num=3" {
                label { 
                    Options for LDOS (plot_num=3): 
                    LDOS is plotted on grid [emin, emax] with spacing delta_e.
                }
                
                var emin -type REAL {
                    default e_fermi
                    info {
                        lower boundary of energy grid (in eV).

                        Defaults to Fermi energy.
                    }
                }
                
                var emax -type REAL {
                    status OPTIONAL 
                    info {
                        upper boundary of energy grid (in eV).

                        Defaults to Fermi energy.
                    }
                }

                var delta_e -type REAL {
                    default 0.1
                    status OPTIONAL 
                    info {
                        spacing of energy grid (in eV).
                    }
                }

                var degauss_ldos -type REAL {
                    default {degauss (converted to eV)}
                    status OPTIONAL 
                    info {
                        broadening of energy levels for LDOS (in eV).

                        Defaults to broadening degauss specified for electronic smearing
                        in pw.x calculation.
                    }
                }
            }
            
            elsewhen -test "plot_num=5" {
                label {
                    Options for STM images (plot_num=5): 
                }
                
                var sample_bias -type REAL {
                    info {
                        the bias of the sample (Ry) in stm images
                    }
                }
                
            }
            
            elsewhen -test "plot_num=7" {
                label { 
                    Options for |psi|^2 (plot_num=7): 
                }

                dimension kpoint -start 1 -end 2 -type INTEGER {
                    info {
                        Unpolarized and noncollinear case:
                                k-point(s) to be plotted
                        LSDA:
                                k-point(s) and spin polarization to be plotted
                                (spin-up and spin-down correspond to different k-points!)
                        
                        To plot a single kpoint ikpt, specify kpoint=ikpt or kpoint(1)=ikpt
                        To plot a range of kpoints [imin, imax], specify kpoint(1)=imin and kpoint(2)=imax
                    }
                }
                
                dimension kband -start 1 -end 2 -type INTEGER {
                    info { 
                        Band(s) to be plotted.
			
                        To plot a single band ibnd, specify kband=ibnd or kband(1)=ibnd
                        To plot a range of bands [imin, imax], specify kband(1)=imin and kband(2)=imax
                    }
                }
                
                var lsign -type LOGICAL {
                    info {
                        if true and k point is Gamma, plot |psi|^2 sign(psi)
                    }
                }
                
                dimension spin_component -start 1 -end 2 -type INTEGER {
                    default 0
                    status OPTIONAL
                    info {
                        @b {Noncollinear case only:}
                        plot the contribution of the given state(s) to the charge 
                        or to the magnetization along the direction(s) indicated 
                        by spin_component:
                                0 = charge (default), 
                                1 = x, 
                                2 = y, 
                                3 = z.

                        Ignored in unpolarized or LSDA case

                        To plot a single component ispin, specify spin_component=ispin or spin_component(1)=ispin
                        To plot a range of components [imin, imax], specify spin_component(1)=imin and spin_component(2)=imax
                    }
                }
            }
            
            elsewhen -test "plot_num=10" {
                label { 
                    Options for ILDOS (plot_num=10): 
                }
                
                var emin -type REAL {
                    info {
                        lower energy boundary (in eV)
                    }
                }
                
                var emax -type REAL {
                    info {
                        upper energy boundary (in eV),
                        i.e. compute ILDOS from @ref emin to @ref emax
                    }
                }
                
                var spin_component -type INTEGER {
                    default 0
                    info {
                        for LSDA case only: plot the contribution to ILDOS of
                        0 = spin-up + spin-down (default)
                        1 = spin-up   only
                        2 = spin-down only
                    }
                }           
            }
            
            elsewhen -test "plot_num=13" {
                label { 
                    Options for noncollinear magnetization (plot_num=13): 
                } 
                
                var spin_component -type INTEGER {
                    default 0 
                    info {
                        0 = absolute value (default value)
                        1 = x component of the magnetization
                        2 = y component of the magnetization
                        3 = z component of the magnetization
                    }
                }
            }

            elsewhen -test "plot_num=17" {
                label { 
                    Options for reconstructed charge density (plot_num=17): 
                } 
                
                var spin_component -type INTEGER {
                    default 0
                    info {
                        0 = total charge (default value),
                        1 = spin up charge,
                        2 = spin down charge.
                    }
                }
            }

            elsewhen -test "plot_num=22" {
                label {
                    Options for kinetic energy density (plot_num=22),
                    LSDA case only:
                }

                var spin_component -type INTEGER {
                    default 0
                    info {
                        0 = total density (default value),
                        1 = spin up density,
                        2 = spin down density.
                    }
                }
            }

            #message { 
            #   Unfinished and untested option:
            #   
            #   plot_num = 14, 15, 16  polarisation along x, y, z respectively.
            #   epsilon  = macroscopic dielectric constant
            #}
        }
    }
    # END of namelist &INPUTPP


    # namelist PLOT

    namelist PLOT {
        
        var nfile -type INTEGER {
            default 1 
            status OPTIONAL 
            info {
                the number of data files to read
            }
        }
        
        group {
            
            dimension filepp -start 1 -end nfile -type CHARACTER {
                default { filepp(1)=filplot } 
                info {
                    nfile = 1 : file containing the quantity to be plotted
                    nfile > 1 : see @ref weight
                }
            }
            
            dimension weight -start 1 -end nfile -type REAL {
                default { weight(1)=1.0 } 
                info {
                    weighing factors: assuming that rho(i) is the quantity
                    read from filepp(i), the quantity that will be plotted is:
                    
                    weight(1)*rho(1) + weight(2)*rho(2) + weight(3)*rho(3) + ...
                }
            }   
            
            message {
                @b BEWARE: atomic coordinates are read from the first file;
                        if their number is different for different files,
                        the first file must have the largest number of atoms
            }     
        }
        
        var iflag -type INTEGER {
            info {
                0 = 1D plot of the spherical average
                1 = 1D plot
                2 = 2D plot
                3 = 3D plot
                4 = 2D polar plot on a sphere
            }
        }
        
        var output_format -type INTEGER {
            info {
                (ignored on 1D plot)
                
                0  = format suitable for gnuplot   (1D)
                
                1  = obsolete format no longer supported
                
                2  = format suitable for plotrho   (2D)
                
                3  = format suitable for XCRYSDEN  (2D or user-supplied 3D region)
                
                4  = obsolete format no longer supported
                
                5  = format suitable for XCRYSDEN  (3D, using entire FFT grid)

                6  = format as gaussian cube file  (3D)
                     (can be read by many programs)

                7  = format suitable for gnuplot   (2D) x, y, f(x,y)
            }
        }

        var fileout -type CHARACTER {
            default { standard output } 
            info {
                name of the file to which the plot is written
            }   
        }

        var interpolation -type CHARACTER {
            default { 'fourier' }
            options {
                info {
                    Type of interpolation:
                }
                opt -val 'fourier' {}
                opt -val 'bspline' { (EXPERIMENTAL) }
            }
        }

        choose {            
            when -test "iflag = 0 or 1" {
                label { the following variables are REQUIRED: } 
                
                dimension e1 -start 1 -end 3 -type REAL {
                    info {
                        3D vector which determines the plotting line (in alat units)
                    }
                }
                
                dimension x0 -start 1 -end 3  -type REAL {
                    info {
                        3D vector, origin of the line (in alat units)
                    }
                }
                
                var nx -type INTEGER {
                    info {
                        number of points in the line:
                        
                        rho(i) = rho( x0 + e1 * (i-1)/(nx-1) ), i=1, nx
                    }
                }
            }       

            elsewhen -test "iflag = 2" {
                label { the following variables are REQUIRED: } 
                
                dimensiongroup  -start 1 -end 3 -type REAL {
                    dimension e1
                    dimension e2
                    info {
                        3D vectors which determine the plotting plane (in alat units)

                        BEWARE: @b e1 and @b e2 must be orthogonal
                    }
                }
                
                dimension x0 -start 1 -end 3 -type REAL {
                    info {
                        3D vector, origin of the plane (in alat units)
                    }
                }
                
                vargroup -type INTEGER {
                    var nx
                    var ny
                    info {
                        Number of points in the plane:
                        
                        rho(i,j) = rho( x0 + e1 * (i-1)/(nx-1)
                                        + e2 * (j-1)/(ny-1) ), i=1,nx ; j=1,ny
                    }
                }           
            }       
            
            elsewhen -test "iflag = 3" {
                label { the following variables are OPTIONAL: } 
                
                dimensiongroup -start 1 -end 3 -type REAL {
                    dimension e1
                    dimension e2
                    dimension e3
                    info {
                        3D vectors which determine the plotting parallelepiped
                        (if present, must be orthogonal)

                        @ref e1, @ref e2, and @ref e3 are in alat units !
                    }
                }
                
                dimension x0 -start 1 -end 3 -type REAL {
                    info {
                        3D vector, origin of the parallelepiped

                        @ref x0 is in alat units !
                    }
                }
                
                vargroup -type INTEGER {
                    var nx
                    var ny
                    var nz 
                    info {
                        Number of points in the parallelepiped:
                        
                        rho(i,j,k) = rho( x0 + e1 * (i-1)/nx
                                          + e2 * (j-1)/ny
                                          + e3 * (k-1)/nz ),
                                     i = 1, nx ; j = 1, ny ; k = 1, nz

                        - If @ref output_format = 3 (XCRYSDEN), the above variables
                          are used to determine the grid to plot. 
                        
                        - If @ref output_format = 5 (XCRYSDEN), the above variables
                          are ignored, the entire FFT grid is written in the
                          XCRYSDEN format - works for any crystal axis (VERY FAST)
                        
                        - If @ref e1, @ref e2, @ref e3, @ref x0 are present, 
                          and @ref e1, @ref e2, @ref e3 are parallel to xyz 
                          and parallel to crystal axis, a subset of the FFT 
                          grid that approximately covers the parallelepiped
                          defined by @ref e1, @ref e2, @ref e3, @ref x0, is 
                          written - untested, might be obsolete

                        - Otherwise, the required 3D grid is generated from the
                          Fourier components (may be VERY slow)
                    }
                }               
            }       

            elsewhen -test "iflag = 4" {
                label { the following variables are REQUIRED: }
                
                var radius -type REAL {
                    info {
                        Radius of the sphere (alat units), centered at (0,0,0)
                    }
                }
                
                vargroup -type INTEGER {
                    var nx
                    var ny 
                    info {
                        Number of points in the polar plane:

                        phi(i)   = 2 pi * (i - 1)/(nx-1), i=1, nx
                        theta(j) =   pi * (j - 1)/(ny-1), j=1, ny
                    }
                }                               
            }   
        }
    }
    # END of namelist PLOT
}
