2020/03/12 by David W. Small, Small, David W.
Materials Science · Physics and Astronomy · #Advanced Chemical Physics Studies #Catalytic Processes in Materials Science #Chemical Physics (physics.chem-ph) #FOS: Physical sciences #Machine Learning in Materials Science
paper · pdf · doi:10.48550/arxiv.2003.06088
openalex publication_date 2020/03/12 · openalex created_date 2025/10/10 · openalex updated_date 2026/07/28
The focus of this work is OS-CCSD-SPT(2), which is a second-order similarity\ntransformed perturbation theory correction to opposite spin coupled cluster\nsingles doubles, where in the latter the same-spin amplitudes are removed and\nthe opposite-spin ones are solved self consistently. We demonstrate that, for\nnon-multireference molecules, OS-CCSD-SPT(2) produces relative energies that\nrival the accuracy of higher-order methods like CCSD(T). For example, using\nPBE0 orbitals in the reference, OS-CCSD-SPT(2) exhibits a mean absolute\ndeviation (MAD) of 0.66 kcal/mol with respect to CCSD(2) benchmark values for\nthe non-multireference subset of W4-08 atomization energies (c.f. a MAD > 6\nkcal/mol for CCSD). OS-CCSD-SPT(2) is free of empirical parameters, has an\ninstrinsic scaling of O(N6), and makes no use of triples. It is also\nnaturally amenable to higher order corrections: the associated third-order\ncorrection, OS-CCSD-SPT(3), which does involve connected triples and\nquadruples, exhibits a MAD of 0.44 kcal/mol for the same benchmark.\n