quantum-espresso/PP/Doc/INPUT_BANDS.xml

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<?xml version="1.0" encoding="ISO-8859-1"?>
<?xml-stylesheet type="text/xsl" href="input_xx.xsl"?>
<!-- FILE AUTOMATICALLY CREATED: DO NOT EDIT, CHANGES WILL BE LOST -->
<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 (including the nonlocal potential
contribution i*m*[V_nl,x])
<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>.
The matrix elements include the contribution from the nonlocal
potential, i*m*[V_nl, x]. In other words, the calculated matrix elements
are those of the velocity operator i*m*[H, x] times mass, not those of
the true momentum operator.
</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>