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Coupled Cluster and Møller-Plesset Perturbation Theory Calculations of Noncovalent Intermolecular Interactions using
Jonas Boström1, Michal Pitoňák2, Francesco Aquilante3
1Department of Theoretical Chemistry, Chemical Center, Lund University, P.O. Box 124 S-221 00 Lund, Sweden.
Abstract:
We compute noncovalent intermolecular interaction energies for the S22 test set [Phys. Chem. Chem. Phys.2006, 8, 1985-1993] of molecules at the Møller-Plesset and coupled cluster levels of supermolecular theory using density fitting (DF) to approximate all two-electron integrals. The error due to the DF approximation is analyzed for a range of auxiliary basis sets derived from Cholesky decomposition (CD) in conjunction with correlation consistent and atomic natural orbital valence basis sets. A Cholesky decomposition threshold of 10(-4)Eh for full molecular CD and its one-center approximation (1C-CD) generally yields errors below 0.03 kcal/mol, whereas 10(-3)Eh is sufficient to obtain the same level of accuracy or better with the atomic CD (aCD) and atomic compact CD (acCD) auxiliary basis sets. Comparing to commonly used predefined auxiliary basis sets, we find that while the aCD and acCD sets are larger by a factor of 2-4 with triple-ζ AO basis sets, they provide results 1-2 orders of magnitude more accurate.
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