Is it possible to feed MP2 NOs into an MCSCF calculation (CASSCF specifically)? MP2 NOs seem to be better suited for constructing an active space than MOs from an SCF calculation.
I could not find any commands for that in the DETCI module documentation, but maybe there is a workaround?
Maybe you can send me the link to the example if you have time?
Also, I know that you can pass a reference wavefunction to the energy(…) command but the MP2 wavefunction is the same as SCF wavefunction, so this doesn’t help.
At a laptop now, this looks like a problem on our end. You can set mcscf_guess mp2 which will give you a MP2 natural orbital guess. The energy command is not a good place for densities as it is often much more costly to compute a methods density than energy. You can check out the rasci-ne for an example on passing wavefunction densities.
Hi, sadly it’s still not working for me. If I run this script:
molecule {
O
H 1 r
H 1 r 2 a
symmetry c1
r = 1.00
a = 103.1
}
set {
basis cc-pvdz
nat_orbs true
d_convergence 9
}
set detci {
restricted_docc [1]
active [6]
restricted_uocc [17]
mcscf_diis_start 20
mcscf_maxiter 100
}
set mcscf_guess scf
energy('casscf')
set mcscf_guess mp2
energy('casscf')
I get two times exactly the same calculation. When the MP2-wavefunction is passed to the casscf-calculation with
Psi4 aborts with the message in the terminal forrtl: severe (71): integer divide by zero. The output-file stops before the first MCSCF-Iteration has finished with no error messages. Is it possible for you to provide me with an example file for a calculation that uses MP2 natural orbitals for a CASSCF calculation?