***,lif non-adiabatic coupling
basis,f=avdz,li=vdz !define basis
r=[10.0,10.5,11.0,11.5,12.0] !define bond distances
dr=0.01 !define increment
geometry={li;f,li,rlif} !define geometry
rlif=3 !first calculation at R=3
{hf;occ,4,1,1} !SCF
{multi;closed,3; !CASSCF, 3 inactive orbitals
wf,12,1;state,2; !Two 1A1 states
orbital,2140.2} !dump orbitals to record 2140.2
do i=1,#r !loop over geometries
rlif=r(i) !set bond distance
{multi;closed,3; !CASSCF, 3 inactive orbitals
wf,12,1;state,2; !Two 1A1 states
orbital,2140.2} !Overwrite previous orbitals by present ones
{ci;state,2;noexc; !CI for 2 states, no excitations
save,6000.2; !save wavefunction to record 6000.2
dm,8000.2} !save (transition) densities to record 8000.2
rlif=r(i)+dr !increment bond distance by dr
{multi;closed,3; !same CASSCF as above
wf,12,1;state,2; !Two 1A1 states
start,2140.2; !start with orbitals from reference geometry
orbital,2141.2; !save orbitals to record 2141.2
diab,2140.2} !generate diabatic orbitals by maximizing the
!overlap with the orbitals at the reference geometry
{ci;state,2;noexc;save,6001.2} !CI for 2 states, wavefunction saved to record 6001.2
{ci;trans,6000.2,6001.2; !Compute overlap and transition density
dm,8100.2} !Save transition density to record 8100.2
rlif=r(i)-dr !repeat at r-dr
{multi;closed,3; !same CASSCF as above
wf,12,1;state,2; !Two 1A1 states
start,2140.2; !start with orbitals from reference geometry
orbital,2142.2; !save orbitals to record 2142.2
diab,2140.2} !generate diabatic orbitals by maximizing the
!overlap with the orbitals at the reference geometry
{ci;state,2;noexc;save,6002.2} !CI for 2 states, wavefunction saved to record 6002.2
{ci;trans,6000.2,6002.2; !Compute overlap and transition density
dm,8200.2} !Save transition density to record 8200.2
{ddr,dr,2140.2,2141.2,8100.2} !compute NACME using 2-point formula (forward difference)
nacme1p(i)=nacme !store result in variable nacme1p
{ddr,-dr,2140.2,2142.2,8200.2} !compute NACME using 2-point formula (backward difference)
nacme1m(i)=nacme !store result in variable nacme1m
{ddr,2*dr !compute NACME using 3-point formula
orbital,2140.2,2141.2,2142.2; !orbital records for R, R+DR, R-DR
density,8000.2,8100.2,8200.2} !transition density records for R, R+DR, R-DR
nacme2(i)=nacme !store result in variable nacme2
end do !end of loop over differend bond distances
nacmeav=(nacme1p+nacme1m)*0.5 !average the two results forward and backward differences
table,r,nacme1p,nacme1m,nacmeav,nacme2 !print a table with results
title,Non-adiabatic couplings for LiF !title for table