Band-structure analysis

This calculation of the band structure is performed optionally after the geometry loop finishes, and the output information written to the SystemLabel.bands file (see below for the format).

BandLinesScale

(string): Specifies the scale of the k vectors given in BandLines and BandPoints below. The options are:

• pi/a (k-vector coordinates are given in Cartesian coordinates, in units of $\pi/a$, where $a$ is the lattice constant)
• ReciprocalLatticeVectors (k vectors are given in reciprocal-lattice-vector coordinates)

Default value: pi/a

Note: You might need to define explicitly a LatticeConstant tag in your fdf file.

BandLines

(data block): Specifies the lines along which band energies are calculated (usually along high-symmetry directions). An example for an FCC lattice is:

     %block BandLines
       1  1.000  1.000  1.000  L        # Begin at L
      20  0.000  0.000  0.000  \Gamma   # 20 points from L to gamma
      25  2.000  0.000  0.000  X        # 25 points from gamma to X
      30  2.000  2.000  2.000  \Gamma   # 30 points from X to gamma
     %endblock BandLines

where the last column is an optional LaTeX label for use in the band plot. If only given points (not lines) are required, simply specify 1 in the first column of each line. The first column of the first line must be always 1.

Use: Used only if SolutionMethod = diagon. The band k points are unrelated and compatible with any k-grid used to calculate the total energy and charge density. This block is overriden by BandPoints if both are present.

Default value: No band energies calculated.

BandPoints

(data block): Band energies are calculated for the list of arbitrary $k$ points given in the block. Units defined by BandLinesScale as for BandLines. The generated Systemlabel.bands file will contain the $k$ point coordinates (in a.u.) and the corresponding band energies (in eV). Example:

     %block BandPoints
        0.000  0.000  0.000   # This is a comment. eg this is gamma
        1.000  0.000  0.000
        0.500  0.500  0.500
     %endblock BandPoints

Use: Used only if SolutionMethod = diagon. The band $k$ points are unrelated and compatible with any k-grid used to calculate the total energy and charge density. If both are present, this block supersedes BandLines.

Default value: No band energies calculated.

WriteKbands

(logical): If .true. it writes the coordinates of the $\vec k$ vectors defined for band plotting, to the main output file.

Use: Only if SolutionMethod is diagon.

Default value: .false. (see LongOutput)

WriteBands

(logical): If .true. it writes the Hamiltonian eigenvalues corresponding to the $\vec k$ vectors defined for band plotting, in the main output file.

Use: Only if SolutionMethod is diagon.

Default value: .false. (see LongOutput)