Counterpoise-Corrected Ab Initio Potential Energy Curves and Analytic Pair Potentials for Ag, Au, and Ni Interacting with He and Ar: A CCSD(T) Benchmark with Machine-Learning Comparison
Year: 2026
Type: preprint
Abstract: Accurate pairwise potentials for coinage-and transition-metal atoms interacting with noble gases are required for molecular dynamics simulations of metal clusters and matrix-isolation environments, yet such potentials are rarely benchmarked with counterpoise-corrected coupledcluster theory. In this work, potential energy curves of Ag, Au, and Ni interacting with He and Ar were computed at the CCSD(T) level using the aug-cc-pVTZ and aug-cc-pVTZ-PP basis sets, with full counterpoise correction and a wavefunction-stability-verified, orbitalcontinuity-chained self-consistent-field protocol. An initial dataset computed with Gaussian 16 was found to contain a spin-multiplicity error for nickel and uncorrected electronic-state discontinuities and was discarded in favor of a complete recomputation with ORCA 6.0.1. Basis-set superposition error was found to account for 59–166% of the well depth even at the aug-cc-pVTZ(-PP) level, and a genuine avoided electronic curve crossing was identified for the Ni–Ar pair near 2.6–3.0 Å, corroborated by both an energy discontinuity and a T1-diagnostic spike. The curves were fitted to the Lennard-Jones, Morse, Buckingham, and Improved Lennard-Jones (ILJ) forms, and to a Gaussian process regression model. The Improved Lennard-Jones and Morse forms were found most reliable classically, while the Lennard-Jones form was poorly constrained for every pair. The Gaussian process regression model outperformed every classical form on every pair. Well depths were found to follow the trend Au > Ag > Ni for both gases, and Ar wells were 11–16 times deeper than He wells, consistent with the larger polarizability of argon.
Source: ChemRxiv
Author: Mohsen Doust Mohammadi
Institution: Cyprus Institute
Language: English
Subfield: Atomic and Molecular Physics, and Optics
Field: Physics and Astronomy
Domain: Physical Sciences
Open Access status: green
OpenAlex ID: W7204816775