Benchmark Electronic Structure Calculations for H3O+(H2O) n , n = 0–5, Clusters and Tests of an Existing 1,2,3-Body Potential Energy Surface with a New 4‑Body Correction

• Published in: Journal of chemical theory and computation 2018-09, Vol.14 (9), p.4553-4566
• Main Authors: Heindel, Joseph P, Yu, Qi, Bowman, Joel M, Xantheas, Sotiris S
• Format: Article
• Language: English
• ISSN: 1549-9618; 1549-9626
• DOI: 10.1021/acs.jctc.8b00598

We report extensive benchmark CCSD­(T) Complete Basis Set (CBS) estimates of the binding energies, structures, and harmonic frequencies of H3O+(H2O) n clusters, n = 0–5, including all currently known low-lying energy isomers. These are used to test a previously reported many-body (up to 3-body interactions) CCSD­(T)-based potential energy surface (PES) for the hydrated proton. A new 4-body term for the hydronium–water–water–water interactions is introduced. This term is aimed at refining the relative energies of isomers of the H3O+(H2O) n , n = 4, 5 clusters. The test results of the revised PES against the benchmark demonstrate the high accuracy of the revised PES.