5.10 Asymptotically Corrected Exchange-Correlation Potentials

5.10.2 Localized Fermi-Amaldi (LFA) Schemes

Another alternative, proposed by Pan, Fang and Chai,701 is to use a localized version of Fermi-Amaldi exchange-correlation functional. The resulting exchange density functional, whose functional derivative has the correct -1/r asymptotic behavior, can be directly added to any semi-local density functional. Three variants of this method were proposed in Ref. 701. The simplest of these, the strictly-localized Fermi-Amaldi (LFAs) scheme, is implemented in Q-Chem, for molecules consisting of atoms with Z≤55.

Example 5.20  LFAs-PBE single-point TD-DFT calculation with water molecule

$comment
   Use LFAs-PBE potential for ground-state calculations, followed by
   TDDFT calculations with an adiabatic PBE XC kernel.
$end

$molecule
   0  1
   O
   H1  O  oh
   H2  O  oh  H1  hoh

   oh  =   1.0
   hoh = 110.0
$end.

$rem
   JOBTYPE       sp
   EXCHANGE      gen
   BASIS         6-311(2+,2+)G**
   CIS_N_ROOTS   30
   RPA           true
$end

$xc_functional
   X   PBE   1.0
   C   PBE   1.0
   X   LFAs  1.0
$end