MOLPRO

31 EXPLICITLY CORRELATED METHODS 242
It is then more efficient to do the a DF-MP2 calculation separately and
compute the total energy as the sum of the DF-MP2 energy and the
F12 energy
Further options for density fitting are described in section 15, and further options to choose the
ansatz in section 31.7.
Typical inputs for calculations with local approximations are:
!parameters for local density fitting:
DFIT,LOCFIT_F12=1,FITDOM_MP2=1,IDOMAUX_MP2=3,DSCREEN=1
!LMP2-F12(loc) with local RI:
{DF-LMP2-F12,ANSATZ=3*A(LOC),DOMSEL=0.985,RAODOM=5,PAIRS=WEAK}
This would perform a local MP2 with a Boughton-Pulay domain completeness criterion of
0.985. In the F12 part, distant pairs are not included (PAIRS=WEAK) and the local projector is
used (USEPAO=1, default). Local density fitting and local RI approximations are used.
A corresponding non-local calculation (still using localized orbitals and the diagonal ansatz)
would be
{DF-LMP2-F12,ANSATZ=3*A(LOC),DOMSEL=1.0,USEVRT=1,NOMP2=1}
ecorr_F12=ef12
{DF-MP2}
ecorr_MP2=energy-energr
ecorr_MP2_F12=ecorr_MP2+ecorr_F12
!mp2 correlation energy
!total correlation energy
Note: The use of local DF and RI domains is still experimental and should be use with care!
31.12 Variables set by the F12 programs
The following variables are set by the F12 programs:
ENERGR
ENERGY
ENERGC
Reference energy. This includes the perturbative CABS singles correction
if computed.
Total energy of the requested method (including the F12 and singles
corrections). ENERGY(1) and ENERGY(2) hold the F12A and
F12B values, respectively (if both are computed).
Total CCSD-F12 energies in ccsd-f12 or uccsd-f12 calculations. ENERGC(1)
and ENERGC(2) hold the F12A and F12B values, respectively (if
both are computed). The difference of ENERGY and ENERGC is the
triples energy contribution.
ENERGT Triples energy contribution. This is a vector. The corresponding
methods are stored in METHODT (strings).
EMP2
EMP2 SCS
Total MP2 energy (excluding F12 correction, but including the singles
correction).
Total SCS-MP2 energy (excluding F12 correction, but including the
singles correction).