Molcas Forum

huangtf

Member

Registered: 2017-04-23

Posts: 18

Single-point CASSCF/CASPT2

Dear all,

I have two questions about “Single-point multiconfigurational complete active space (CASSCF) and second-order perturbation theory (CASPT2) calculations were performed at the DFT-optimized geometries.”:
1. If I want to see some bonding and antibonding orbitals, just single-point CASSCF is enough, do you think so?
2. If I want to consider energies of different geometries, except for the intention in question 1, single-point CASSCF/CASPT2 is necessary, do you agree with me?

Please help me out! Thank you very much!

Sincerely yours,
huangtf

cymantren

Member

Registered: 2017-09-18

Posts: 37

Re: Single-point CASSCF/CASPT2

Dear Huangtf,

I don't understand your questions completly, but maybe I am wrong.
If you just want to see orbitals-bondig and antibonding-a simple SCF/UHF-calculation produces these results. Do you mean "the bonding/antibonding orbitals" of your molecule of interest, then you have to find out the active space.

Yor remarks are to less to find out what's really your problem.
However, I am also a beginner with OPENMOLCAS and this is a Forum, which all participants try to help each other.

Please be more detailed !

Greetings

Alfred Güthler

huangtf

Member

Registered: 2017-04-23

Posts: 18

Re: Single-point CASSCF/CASPT2

Dear Alfred,

Do you mean "the bonding/antibonding orbitals" of your molecule of interest, then you have to find out the active space.

Yes.

Your remarks are too less to find out what's really your problem.

Please see this paper (DOI: 10.1021/ic202503h), I don’t know the difference between CASSCF natural orbitals and CASPT2 natural orbitals.

Yours sincerely,
huangtf