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<input_description distribution="Quantum Espresso" package="PWscf" program="bands.x" >
   <toc>
   </toc>
   <intro>
<b>Purpose of bands.x:</b>
   Re-order bands, computes band-related properties. Currently,
   re-ordering can be done with two different algorithms:
   (a) by maximising the overlap with bands at previous k-point
   (b) by computing symmetry properties of each wavefunction
   Bands-related properties that can be computed are currently
   (a) The expectation value of the spin operator on each spinor
       wave-function (noncolinear case only)
   (b) The expectation value of p

The input data can be read from standard input or from file using
command-line options &quot;bands.x -i file-name&quot; (same syntax as for pw.x)

Output files:
- file <ref>filband</ref> containing the band structure, in a format
  suitable for plotting code &quot;plotband.x&quot;
- file &quot;filband&quot;.rap (if <ref>lsym</ref> is .t.)  with symmetry information,
  to be read by plotting code &quot;plotband.x&quot;
- if (<ref>lsigma</ref>(i)): file &quot;filband&quot;.i, i=1,2,3, with expectation values
  of the spin operator in the noncolinear case
- file &quot;filband&quot;.gnu with bands in eV, directly plottable using gnuplot
- file <ref>filp</ref> with matrix elements of p

<b>Structure of the input data:</b>
============================

   <b>&amp;BANDS</b>
     ...
   <b>/</b>
   </intro>
   <namelist name="BANDS" >
      <var name="prefix" type="CHARACTER" >
         <default> &apos;pwscf&apos;
         </default>
         <info>
prefix of files saved by program pw.x
         </info>
      </var>
      <var name="outdir" type="CHARACTER" >
         <info>
directory containing the input data, i.e. the same as in pw.x
         </info>
         <default>
value of the ESPRESSO_TMPDIR environment variable if set;
current directory (&apos;./&apos;) otherwise
         </default>
      </var>
      <var name="filband" type="CHARACTER" >
         <default> &apos;bands.out&apos;
         </default>
         <info>
file name for band output (to be read by &quot;plotband.x&quot;)
         </info>
      </var>
      <var name="spin_component" type="INTEGER" >
         <info>
In the lsda case select:

   1 = spin-up
   2 = spin-down
         </info>
      </var>
      <dimension name="lsigma" start="1" end="3" type="LOGICAL" >
         <info>
If true computes expectation values of the spin operator
on the spinor wave-functions (only in the noncollinear case),
writes them to a file &quot;filband&quot;.i, i=1,2,3
         </info>
      </dimension>
      <var name="lp" type="LOGICAL" >
         <default> .false.
         </default>
         <info>
If .true. matrix elements of the momentum operator p between
conduction and valence bands are computed and written to file
specified in <ref>filp</ref>
         </info>
      </var>
      <var name="filp" type="CHARACTER" >
         <default> &apos;p_avg.dat&apos;
         </default>
         <info>
If <ref>lp</ref> is set to .true., file name for matrix elements of p
         </info>
      </var>
      <var name="lsym" type="LOGICAL" >
         <default> .true.
         </default>
         <info>
If .true. the bands are classified according to the
irreducible representations of the small group of k.
A file &quot;filband&quot;.rap with the same format of &quot;filband&quot;
is written, for usage by &quot;plotband.x&quot;
         </info>
      </var>
      <var name="no_overlap" type="LOGICAL" >
         <default> .true.
         </default>
         <info>
If .false., and if <ref>lsym</ref> is .false., writes the eigenvalues
in the order that maximises overlap with the neighbor k-points
         </info>
      </var>
      <var name="plot_2d" type="LOGICAL" >
         <default> .false.
         </default>
         <info>
If .true. writes the eigenvalues in the output file
in a 2D format readable by gnuplot. Band ordering is not
changed. Each band is written in a different file called
filband.# with the format:
<i>
   xk, yk, energy
   xk, yk, energy
   ..  ..  ..
</i>
energies are written in eV and xk in units 2\pi/a.
         </info>
      </var>
      <vargroup type="INTEGER" >
         <var name="firstk" >
         </var>
         <var name="lastk" >
         </var>
         <info>
if <ref>lsym</ref>=.true. makes the symmetry analysis only for k
points between firstk to lastk
         </info>
      </vargroup>
   </namelist>
</input_description>
