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Some basis sets are said to be "correlation consistent". What does it mean in practice ?

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Wikipedia has an answer here:

http://en.wikipedia.org/wiki/Basis_set_(chemistry)#Correlation-consistent_basis_sets

Edit: adding introductory text from Wikipedia:

Some of the most widely used basis sets are those developed by Dunning and coworkers, since they are designed to converge systematically to the complete-basis-set (CBS) limit using empirical extrapolation techniques. For first- and second-row atoms, the basis sets are cc-pVNZ where N=D,T,Q,5,6,... (D=double, T=triples, etc.). The 'cc-p', stands for 'correlation-consistent polarized' and the 'V' indicates they are valence-only basis sets. They include successively larger shells of polarization (correlating) functions (d, f, g, etc.). More recently these 'correlation-consistent polarized' basis sets have become widely used and are the current state of the art for correlated or post-Hartree-Fock calculations.

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  • $\begingroup$ Wikipedia isn't really answering the question in a physical way. That "answer" is just a summary of the recipe used to achieve the desired physical property. $\endgroup$ – Jeff Apr 13 '13 at 20:38
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I recommend reading Thom Dunning Jr. “Gaussian basis sets for use in correlated molecular calculations. I. The atoms boron through neon and hydrogen.” J. Chem. Phys. 90, 1007 (1989) by for an answer to this question.

The abstract says the following:

This leads to the concept of correlation consistent basis sets, i.e., sets which include all functions in a given group as well as all functions in any higher groups.

This refers to the telescoping nature of the angular momentum levels used, e.g. 5s4p3d2f1g.

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  • $\begingroup$ Updated link or full reference? $\endgroup$ – Peter Bingham Apr 12 at 13:27
  • $\begingroup$ Sorry about that. I’m not used to JChP breaking links. I added the article details and used DOI link instead. $\endgroup$ – Jeff Apr 12 at 14:02

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