4. Exchange Correlation Functionals

The exchange-correlation functional is specified in the CLUSTER and/or SYMBOL files. The user can currently choose to use the following list of functionals:

NONE: No functional will be used PERZUN: PERDEW-ZUNGER 81 CEPERL: CEPERLEY

RPA: RPA

WIGNER: WIGNER

GUNLUN: GUNNARSSON-LUNDQVIST

PW91: PERDEW-WANG 92

PBE: PERDEW-BURKE-ERNZERHOF 96

REVPBE: REV PBE

RPBE: R PBE

B88: BECKE 88

The string needed to choose them is as follows:

LDA-PW91*LDA-PW91

This selects the LDA-PW91 exchange functional and the LDA-PW91 correlation functional. To use the PBE GGA functional, use: GGA-PBE*GGA-PBE

If the user wants to run GGA-PBE exchange-only, the string will be : GGA-PBE*GGA-NONE