LIBXC1 Pn

LIBXC1_Pn = [real]

Description: LIBXC1_Pn and LIBXC2_Pn, where n=1, 2, ... allow to specify the values of the parameters in functionals implemented in Libxc called with LIBXC1 and LIBXC2, respectively.

For many functionals implemented in Libxc it is possible to specify parameters if one does not want to use the default ones. If a functional from Libxc has parameters that can be modified, then they are listed below "Parameters of Libxc functionals:" as Pn (n=1, 2, ...) in OUTCAR, where the default values are also shown

The sum of the fraction of the exact exchange and LDA exchange is always 1.0, and it is not possible to set the amount of LDA exchange indepently. Examples: if AEXX=0.25, 1/4 of the exact exchange is used, and 3/4 of the LDA exchange is added. For AEXX=0.5, half of the exact exchange is used, and one half of the LDA exchange is added.

The amount of LDA correlation included in the hybrid functional can be specified through the ALDAC-tag.

The amount of gradient correction to the exchange and the correlation contributions can be set indepently, however (some popular hybride functionals for instance use only 0.8 of the gradient contribition to the exchange). The GGA flags AGGAX and AGGAC are only used if GGA is already selected (for LDA type calculations no gradient correction will be added regardless of values is used for AGGAX and AGGAC).