Multiwfn forum / About quickCBS

Re: About quickCBS

dummy@example.com (Antuán) — Wed, 16 Dec 2020 11:25:28 +0000

OK. Have a nice day!!

Re: About quickCBS

dummy@example.com (sobereva) — Wed, 16 Dec 2020 00:05:58 +0000

No. There is no simple way of evaluating CBS estimation.

Re: About quickCBS

dummy@example.com (Antuán) — Tue, 15 Dec 2020 23:26:30 +0000

Many thanks Tian. And the last question, do quickCBS calculate the error of the CBS estimation?

Re: About quickCBS

dummy@example.com (sobereva) — Tue, 15 Dec 2020 23:20:28 +0000

ORCA itself directly supports basis set extrapolation via "extrapolation" keyword, therefore I don't plan to make quickCBS support ORCA.
For example, "! CCSD(T) Extrapolate(2/3) tightSCF" will automatically calculate CCSD(T)/CBS energy by cc-pVDZ->cc-pVTZ extrapolation.

Re: About quickCBS

dummy@example.com (Antuán) — Tue, 15 Dec 2020 22:03:04 +0000

Many thanks!!! And do you will have soon support for ORCA outputs?

Re: About quickCBS

dummy@example.com (sobereva) — Tue, 15 Dec 2020 21:52:11 +0000

You should use an appropriate level to optimize the geometry, commonly DFT with a 3-zeta quality basis set is adquate. For organic systems, usually you can use such as B3LYP/def-TZVP to optimize the geometry. I cannot give you detailed advice without information of your system and your computational resource.

About quickCBS

dummy@example.com (Antuán) — Tue, 15 Dec 2020 21:48:50 +0000

Dear Tian,

you have a kindly way to get the CBS limit from CCSD(T) single point calculations, but you don't talk about the starting geometry you need for this task. Do you have a preferred choice?

Thanks in advance,
Antonio