    ------------------------------------------------------------------------
    INPUT FILE DESCRIPTION

    Program: bands.x / PWscf / Quantum Espresso
    ------------------------------------------------------------------------

    Purpose of bands.x:
        Rewrite the bands ordering them using the overlap
        of the wave-functions on neighbor k points
        and calculate properties of each eigen-function.

    Presently it can calculate:

       (a) The expectation value of the spin operator on each spinor
           wave-function.
       (b) The symmetry properties of each wavefunction. With this option
           the bands are not ordered according to the overlap.

    The input data of this program are read from standard input
    or from a file and have the following format:

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

       &BANDS
         ...
       /

    ========================================================================
    NAMELIST: &BANDS

       +--------------------------------------------------------------------
       Variable:       prefix

       Type:           CHARACTER
       Description:    prefix of files saved by program pw.x
       +--------------------------------------------------------------------

       +--------------------------------------------------------------------
       Variable:       outdir

       Type:           CHARACTER
       Description:    directory containing the input data,
                       i.e. the same as in pw.x
       Default:        value of the ESPRESSO_TMPDIR environment variable if set;
                       current directory ('./') otherwise
       +--------------------------------------------------------------------

       +--------------------------------------------------------------------
       Variable:       filband

       Type:           CHARACTER
       Description:    file "filband" contains the bands
       +--------------------------------------------------------------------

       +--------------------------------------------------------------------
       Variable:       spin_component

       Type:           INTEGER
       Description:    In the lsda case select:

                          1 = spin-up
                          2 = spin-down
       +--------------------------------------------------------------------

       +--------------------------------------------------------------------
       Variable:       lsigma(i), i=1,3

       Type:           LOGICAL
       Description:    If true writes a file filband.i with the expectation
                       values of the spin operator on the spinor wave-functions.
                       (only in the noncollinear case).
       +--------------------------------------------------------------------

       +--------------------------------------------------------------------
       Variable:       lsym

       Type:           LOGICAL
       Description:    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.
       +--------------------------------------------------------------------

       +--------------------------------------------------------------------
       Variable:       no_overlap

       Type:           LOGICAL
       Default:        .false.
       Description:    If .true. writes the eigenvalues in the output file
                       without changing their order.
       +--------------------------------------------------------------------

       +--------------------------------------------------------------------
       Variable:       plot_2d

       Type:           LOGICAL
       Default:        .false.
       Description:    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.
       +--------------------------------------------------------------------

       +--------------------------------------------------------------------
       Variables:      firstk, lastk

       Type:           INTEGER
       Description:    if lsym=.true. makes the symmetry analysis only for k
                       points between firstk to lastk
       +--------------------------------------------------------------------

    ===END OF NAMELIST======================================================