About quickCBS

Antuán · 2020-12-15 21:48:50

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

sobereva · 2020-12-15 21:52:11

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.

Antuán · 2020-12-15 22:03:04

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

sobereva · 2020-12-15 23:20:28

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.

Antuán · 2020-12-15 23:26:30

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

sobereva · 2020-12-16 00:05:58

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

Antuán · 2020-12-16 11:25:28

OK. Have a nice day!!

Multiwfn forum

#1 2020-12-15 21:48:50

About quickCBS

#2 2020-12-15 21:52:11

Re: About quickCBS

#3 2020-12-15 22:03:04

Re: About quickCBS

#4 2020-12-15 23:20:28

Re: About quickCBS

#5 2020-12-15 23:26:30

Re: About quickCBS

#6 2020-12-16 00:05:58

Re: About quickCBS

#7 2020-12-16 11:25:28

Re: About quickCBS

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