Post-CCSD(T) corrections in the S66 noncovalent interactions benchmark
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arXiv
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| Format: | Preprint |
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2024
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| _version_ | 1866915112355364864 |
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| author | Semidalas, Emmanouil Boese, A. Daniel Martin, Jan M. L. |
| author_facet | Semidalas, Emmanouil Boese, A. Daniel Martin, Jan M. L. |
| contents | For noncovalent interactions, it is generally assumed that CCSD(T) is nearly the exact solution within the 1-particle basis set. For the S66 noncovalent interactions benchmark, we present for the majority of species CCSDT and CCSDT(Q) corrections with a polarized double-zeta basis set. For hydrogen bonds, pure London complexes, and mixed-influence complexes, CCSD(T) benefits from error cancellation between (usually repulsive) higher-order triples, $T_3 - (T)$, and (almost universally attractive) connected quadruples, (Q). For $π$-stacking complexes, this cancellation starts breaking down and CCSD(T) overbinds; CCSD(T)$_Λ$ corrects the problem at the expense of London complexes. A fairly simple two-parameter model predicts CCSDT(Q)--CCSD(T) differences to 0.01 kcal/mol RMS, requiring no calculations that scale more steeply than $O(N^7)$. |
| format | Preprint |
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arxiv_https___arxiv_org_abs_2411_12004 |
| institution | arXiv |
| publishDate | 2024 |
| record_format | arxiv |
| spellingShingle | Post-CCSD(T) corrections in the S66 noncovalent interactions benchmark Semidalas, Emmanouil Boese, A. Daniel Martin, Jan M. L. Chemical Physics For noncovalent interactions, it is generally assumed that CCSD(T) is nearly the exact solution within the 1-particle basis set. For the S66 noncovalent interactions benchmark, we present for the majority of species CCSDT and CCSDT(Q) corrections with a polarized double-zeta basis set. For hydrogen bonds, pure London complexes, and mixed-influence complexes, CCSD(T) benefits from error cancellation between (usually repulsive) higher-order triples, $T_3 - (T)$, and (almost universally attractive) connected quadruples, (Q). For $π$-stacking complexes, this cancellation starts breaking down and CCSD(T) overbinds; CCSD(T)$_Λ$ corrects the problem at the expense of London complexes. A fairly simple two-parameter model predicts CCSDT(Q)--CCSD(T) differences to 0.01 kcal/mol RMS, requiring no calculations that scale more steeply than $O(N^7)$. |
| title | Post-CCSD(T) corrections in the S66 noncovalent interactions benchmark |
| topic | Chemical Physics |
| url | https://arxiv.org/abs/2411.12004 |