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arXiv · 2506.10780

Slimmer Geminals For Accurate F12 Electronic Structure Models

Samuel R. Powell·Kshitijkumar A. Surjuse·Bimal Gaudel·Edward F. Valeev
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Abstract

The Slater-type F12 geminal lengthscales originally tuned for the second-order M{\o}ller-Plesset F12 method are too large for higher-order F12 methods formulated using the SP (diagonal fixed-coefficient spin-adapted) F12 ansatz. The new geminal parameters reported herein reduce the basis set incompleteness errors (BSIE) of absolute coupled-cluster singles and doubles F12 correlation energies by a significant - and increasing with the cardinal number of the basis - margin. The effect of geminal reoptimization is especially pronounced for the cc-pVXZ-F12 basis sets (specifically designed for use with F12 methods) relative to their conventional aug-cc-pVXZ counterparts. The BSIEs of relative energies are less affected but substantial reductions can be obtained, especially for atomization energies and ionization potentials with the cc-pVXZ-F12 basis sets. The new geminal parameters are therefore recommended for all applications of high-order F12 methods, such as the coupled-cluster F12 methods and the transcorrelated F12 methods.

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Samuel R. Powell, Kshitijkumar A. Surjuse, Bimal Gaudel, Edward F. Valeev. 2025-06-12. Slimmer Geminals For Accurate F12 Electronic Structure Models. https://doi.org/10.1021/acs.jctc.5c00971

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