Probing the basis set limit for thermochemical contributions of inner-shell correlation: balance of core-core and core-valence contributions*. (18th June 2019)

• Record Type: Journal Article
• Authors: Sylvetsky, Nitai; Martin, Jan M. L.
• Is Part Of: Molecular physics. Volume 117:Number 9/12(2019)
• Page Start: 1078
• Page End: 1087
• Publication Date: 2019-06-18
• Subjects: Core-valence correlation -- inner-shell correlation -- basis set convergence -- thermochemistry -- coupled cluster; Molecules -- Periodicals; Chemistry, Physical and theoretical -- Periodicals; Molécules -- Périodiques; Chimie physique et théorique -- Périodiques; 539.6.05
• DOI: 10.1080/00268976.2018.1478140
• Languages: English
• ISSNs: 0026-8976

Abstract

ABSTRACT: The inner-shell correlation contributions to the total atomisation energies of the W4-17 computational thermochemistry benchmark have been determined at the CCSD( T ) level near the basis set limit using several families of core correlation basis sets, such as aug-cc-pCVnZ ( n = 3–6), aug-cc-pwCVnZ ( n = 3–5) and nZaPa-CV ( n = 3–5). The three families of basis sets agree very well with each other (0.01 kcal/mol RMS) when extrapolating from the two largest available n : however, there are considerable differences in convergence behaviour for the smaller basis sets. nZaPa-CV is superior for the core-core term and awCVnZ for the core-valence term. While the aug-cc-pwCV( T +d)Z basis set of Yockel and Wilson is superior to aug-cc-pwCVTZ, further extension of this family proved unproductive. The best compromise between accuracy and computational cost, in the context of high-accuracy computational thermochemistry methods, is CCSD( T )/awCV{ T, Q }Z, where the { T, Q } notation stands for extrapolation from the awCVTZ and awCVQZ basis set pair. For lower-cost calculations, we recommend a previously proposed combination of CCSD-F12b/cc-pCVTZ-F12 and CCSD( T )/pwCVTZ(no f). While in first-row molecules core-valence correlation on average accounts for over 90% of the inner-shell contribution, in second-row molecules core-core contributions may become important, particularly in systems like P4 and S4 with multiple adjacent second-row atoms. GRAPHICAL ABSTRACT: