Questions about guess read

1

Dear users,

I’m trying to use SCF-optimized or orbital optimized molecular orbital to the following calculation.

In the case of SCF-optimized mo, I could use uhf mo to the following pbe calculation like below.

memory 250 mb

molecule fe
{
2 5
symmetry c1
fe 0 0 0
}
set basis cc-pVQZ
set reference uhf
set e_convergence 1e-8
set d_convergence 1e-8
energy (“scf”)

molecule fe
{
2 5
symmetry c1
fe 0 0 0
}
set basis cc-pVQZ
set reference uhf
set e_convergence 1e-8
set d_convergence 1e-8
set maxiter 0
set guess read
set fail_on_maxiter false
energy (“pbe”)

this input gives me desired value. But how can I use orbital-optimized mp2 or cc orbital (dfocc) like that?

What I mean is, I wonder if there is any way to set initial mo from not-scf converged mo.

Thank you for the help.

2

Any post-scf procedure will take in an incoming wavefunction like so:

omp2_e, omp2_wfn = energy('OMP2', return_wfn=True)
energy('CCSD', ref_wfn = omp2_wfn)

SCF is a bit odd as it originates Wavefunctions rather than using them. We are still working on ways where we can pass Wavefunctions into SCF.

1 Like
3

Thank you for the quick answer.
What I understand is psi4 can use post-HF wfn to the other post-HF ref_wfn and scf_wfn can be used what I did like above one but cannot use post-HF wfn as ref_wfn of SCF and vice versa.
I wonder if I understood your comment right.

4

Yes, any post-SCF Wavefunction can take a Wavefunction (which can be anything). SCF can only be “passed” through the read/write mechanics right now.

5

Could I ask one more question? I obtained converged MO as two ways.

  1. from molden_write
  2. scf_e, scf_wfn = energy(‘scf’, return_wfn=True)
    scf_wfn.Ca().print_out()

In the case of SCF, method 1 and 2 gives same MO but omp2 didn’t.
I got dfocc.molden from molden_write and printed MO inside the output file from
omp2_e, omp2_wfn = energy(‘omp2’, return_wfn=True)
omp2_wfn.Ca().print_out()

In this case, which one is the converged MO???

6

OMP2 apparently writes natural orbitals with the molden_write flag. Ill open an issue that this is not documented correctly.

7

Hi, I’m wondering if pass Wavefunction into SCF is now updated.
Or, is there any way to use the Wavefunction (such as from CC or MBPT) manually?
What I want to do is generating DFT energies from the converged Wavefunction.

8

Not currently. Do you just want the energies without iterating? We can do that Python side.

9

Yes, that’s why I exactly want it. Could you teach me how to do that?

10

Hmm, can you take a try at it using ideas from:

and:

My bandwidth is a bit limited at the moment. Ill be back this weekend and might be able to help more then.