Augment | The basis set augmentation string Augment defines the global augmentation basis set. By default, no augmentation is performed. |
AUGMENT (XAS-I) S (XAS-II)
requests the XAS-I augmentation basis set for all atoms, except sulfur, for which the XAS-II augmentation basis set is used. These are the two augmentation basis sets available in the deMon2k basis set file. XAS-I is typically used for first-row atoms whereas XAS-II is somewhat more extended and, therefore, appropriate for heavier atoms. Note that for reliable XAS spectra the augmentation basis is needed, at least on the core-excited atom. Otherwise the sampling of the continuum and Rydberg states will be too coarse. Augmentation basis sets can also be defined directly in the input file using the format:
Augment SYMBOL Read N L K EXPONENT COEFFICIENT : : EXPONENT COEFFICIENT
The syntax is the same as for the reading of basis sets.