(external) basis sets

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stefan
Posts: 16
Joined: 27 Aug 2013, 16:37
First name(s): Stefan
Last name(s): Knecht

(external) basis sets

Post by stefan » 02 Dec 2014, 10:41

dear all,

please find below a message from the Molcas developers group (announced by Steven Vancoillie, one of the Molcas developers and sysadmins) that was released last weekend concerning the ANO-RCC basis set. There is a bug for the elements C and Th that you should be aware of. The ANO-RCC basis set collection is not part of the Dalton basis set library but using Peter Taylor's conversion tool you can download the ANO-RCC basis set from the EMSL basis set exchange library and easily convert it to Dalton-readable format.
Caution: The entries for C and Th on the EMSL basis set exchange library are also wrong (identical to the Molcas file)!
Please stay tuned for further information.

with best regards,

stefan

announcement:

"
Dear users,

we would like to inform you that two problems have been found in the ANO-rcc basis sets of C and Th. For example, for C, the contraction coefficients are wrong (they are those of N). This can give rise to subtle errors that aren't immediately easy to spot (depending on the number of contracted basis functions chosen). We are currently investigating when this error was introduced (which Molcas version), and how to fix this. We are working to provide users with more detailed information about the problem and to offer a long-term solution.

In the meanwhile, the best course of action is not to use the current ANO-rcc basis set of C (and Th). Ideally, for the first two rows we recommend using ANO-L instead (which has the same primitives, but the contraction did not include scalar relativistic effects).
"

taylor
Posts: 525
Joined: 15 Oct 2013, 05:37
First name(s): Peter
Middle name(s): Robert
Last name(s): Taylor
Affiliation: Tianjin University
Country: China

Re: (external) basis sets

Post by taylor » 02 Dec 2014, 11:19

This very useful, if unfortunate. Can I take this opportunity to emphasize that inclusion of scalar relativistics leads to quite significant changes in contraction coefficients compared to the nonrelativistic case for a given primitive set? That is, if you are using an ANO basis set from any source that was contracted using a nonrelativistic calculation, you should be very wary about using such a basis with, say Douglas-Kroll-Hess for scalar relativistics. Anyone who wants more literature references on this issue is welcome to contact me.

Best regards
Pete

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