I would like to compute the expectation value <Psi' | H | Psi' > where |Psi'> is the multi-determinantal ground-state wave function computed in a previous MRCI with a different Hamiltonian H'.
Is it possible to use the MRCI program with the "start" card to recover the previously saved wave function |Psi'> and to perform only one iteraction in order to compute
<Psi' | H | Psi' > ?
So far, all the tests I have done failed.
For example, in the following simple input where H=H', the second one-iteraction only MRCI does not give the right energy <Psi' | H | Psi' > . It seems that the wave function |Psi'> is not properly recovered by the "start" keyword.
Does anyone know how to proceed?
Best regards,
Julien Toulouse Laboratoire de Chimie Theorique Paris
---------------------- ***, He
geom={He}
basis=vtz
hf; occ,1 wf,2,1,0;
! First MRCI to calculate Psi' ci occ,3,2,2,,2 closed core wf,2,1,0; save,2341.3,2342.3,1; ! save wave function Psi'
! Second MRCI to calculate <Psi'|H|Psi'> ci start,2341.3,1 ! starting wave function Psi' option,maxiti=1,maxit=1 ! no iteration, compute only <Psi'|H|Psi'>
