Output of wavefunctions

The user can optionally request that specific wavefunctions are written to file. These wavefunctions are re-computed after the geometry loop (if any) finishes, using the last (presumably converged) density matrix produced during the last self-consistent field loop (after a final mixing). They are written to the SystemLabel.WFSX file (see below for the format).

Note that the complete set of wavefunctions obtained during the last iteration of the SCF loop will be written to SystemLabel.WFSX if the COOP.write option is in effect (but they might be overwritten by the options below).

Note that the complete set of wavefunctions obtained during the last iteration of the SCF loop will be written to a NetCDF file WFS.nc if the Diag.UseNewDiagk option is in effect.

WaveFuncKPointsScale

(string): Specifies the scale of the k vectors given in WaveFuncKPoints 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

WaveFuncKPoints

(data block): Specifies the k-points at which the electronic wavefunction coefficients are written. An example for an FCC lattice is:

     %block WaveFuncKPoints
     0.000  0.000  0.000  from 1 to 10   # Gamma wavefuncs 1 to 10
     2.000  0.000  0.000  1 3 5          # X wavefuncs 1,3 and 5
     1.500  1.500  1.500                 # K wavefuncs, all
     %endblock WaveFuncKPoints

The number of wavefunction is defined by its energy, so that the first one has lowest energy. The output of the wavefunctions in described in Section

Use: Used only if SolutionMethod = diagon. These k points are unrelated and compatible with any k-grid used to calculate the total energy, charge density and band structure.

Default value: No wavefunctions are written.

WriteWaveFunctions

(logical): If .true. it writes to the output file a list of the wavefunctions actually written to the Systemlabel.WFSX file, which is always produced.

Use: Only if SolutionMethod is diagon.

Default value: .false. (see LongOutput)

The unformatted file SystemLabel.WFSX contains the information of the k-points for which wavefunctions coefficients are written, and the energies and coefficients of each wavefunction which was specified in the input file (see WaveFuncKPoints descriptor above). It also contains information on the atomic species and the orbitals for postprocessing purposes.

NOTE: The WFSX file is in a more compact form than the old WFS, and the wavefunctions are output in single precision. The Util/WFS/wfsx2wfs program can be used to convert to the old format.

The readwf and readwfsx postprocessing utilities programs (found in the Util/WFS directory) read the WFS or WFSX files, respectively, and generate a readable file.