Narrowing the error in electron correlation calculations by basis set re-hierarchization and use of the unified singlet and triplet electron-pair extrapolation scheme: Application to a test set of 106 systems

Abstract

A method previously suggested to calculate the correlation energy at the complete one-electron basis set limit by reassignment of the basis hierarchical numbers and use of the unified singlet- and triplet-pair extrapolation scheme is applied to a test set of 106 systems, some with up to 48 electrons. The approach is utilized to obtain extrapolated correlation energies from raw values calculated with second-order Møller-Plesset perturbation theory and the coupled-cluster singles and doubles excitations method, some of the latter also with the perturbative triples corrections. The calculated correlation energies have also been used to predict atomization energies within an additive scheme. Good agreement is obtained with the best available estimates even when the (d, t) pair of hierarchical numbers is utilized to perform the extrapolations. This conceivably justifies that there is no strong reason to exclude double-zeta energies in extrapolations, especially if the basis is calibrated to comply with the theoretical model.

F2 dimer: Improved intermolecular potential energy surface using ab initio calculations

“…Furthermore, in some cases the requirement of high Random Access Memory (RAM) and disk space cause program and hardware failures. In this regard, different techniques have been developed to estimate the CBS limit using smaller basis sets . In this study, MP2 method has been used to choose the best technique for estimation of the CBS limit.…”

“…One of the problems of this technique is that for X = 2 the CBS limit shows different behavior from that observed using larger basis set. Therefore, effective schemes have been proposed to improve the accuracy of estimation of the CBS limit . To our knowledge, the best and the newest the CBS extrapolation scheme has been proposed by Okoshi et al In this model for the DZ‐level correlation energy, a factor has been introduced to scale the cardinal number.…”

Application of the Unified Singlet and Triplet Electron-Pair Extrapolation Scheme with Basis Set Rehierarchization to Tensorial Properties

“…where, for USTE(x − 1, x), x = d, t, q, p, and h are the hierarchical numbers proposed elsewhere: 18 …”

Revisiting the extrapolation of correlation energies to complete basis set limit

“…The most recent contribution, to the best of our knowledge, was conducted by Varandas and Pansini (VP) . They improved the uniform singlet‐ and triplet‐pair extrapolation scheme, originally developed by the same group, with modified cardinal numbers x , which are referred as hierarchical numbers.…”

“…Calibration of the degradation using the DZ‐level energy in the CBS model would lead to a reduction in computational efforts. Truhlar, Huh and Lee (HL), Bakowies, Varandas and coworkers, and Lutz and Piecuch, proposed effective schemes for improved accuracies in estimation of the CBS limit energies for single‐point and/or potential energy curve calculations.…”