Purpose of bands.x: 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 "bands.x -i file-name" (same syntax as for pw.x)

Output files: - file filband containing the band structure, in a format suitable for plotting code "plotband.x" - file "filband".rap (if lsym is .t.) with symmetry information, to be read by plotting code "plotband.x" - if (lsigma(i)): file "filband".i, i=1,2,3, with expectation values of the spin operator in the noncolinear case - file "filband".gnu with bands in eV, directly plottable using gnuplot - file filp with matrix elements of p (including the nonlocal potential contribution i*m*[V_nl,x])

Structure of the input data: ============================

&BANDS ... /
'pwscf'
prefix of files saved by program pw.x
directory containing the input data, i.e. the same as in pw.x
value of the ESPRESSO_TMPDIR environment variable if set; current directory ('./') otherwise
'bands.out'
file name for band output (to be read by "plotband.x")
In the lsda case select:

1 = spin-up 2 = spin-down
If true computes expectation values of the spin operator on the spinor wave-functions (only in the noncollinear case), writes them to a file "filband".i, i=1,2,3
.false.
If .true. matrix elements of the momentum operator p between conduction and valence bands are computed and written to file specified in filp. 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.
'p_avg.dat'
If lp is set to .true., file name for matrix elements of p
.true.
If .true. the bands are classified according to the irreducible representations of the small group of k. A file "filband".rap with the same format of "filband" is written, for usage by "plotband.x"
.true.
If .false., and if lsym is .false., writes the eigenvalues in the order that maximises overlap with the neighbor k-points
.false.
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: xk, yk, energy xk, yk, energy .. .. .. energies are written in eV and xk in units 2\pi/a.
if lsym=.true. makes the symmetry analysis only for k points between firstk to lastk