DEG THRESHOLD
DEG_THRESHOLD = [real]
| Default: DEG_THRESHOLD | = $2*10^{-3}$ |
Description: DEG_THRESHOLD specifies whether two eigenvalues should be treated as degenerate during wavefunction clustering. DEG_THRESHOLD is specified in units of eV.
This parameter is used to find clusters of wave functions within a given energy range. If it is set too high, non-degenerate eigenvalue pairs may be detected as degenerate pairs. Then, the inverse iteration will attempt to converge them. Ultimately, the program will get stuck and converge poorly. Conversely, too small a value might not detect all degenerate eigenvalues. The most severe problems are caused by very narrow semicore bands.
| Tip: If you experience large drifts in the Born effective charges and adding more k-points does not help, try adjusting this parameter. |