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Argon pair potential at basis set and excitation limits
Konrad Patkowski1, Krzysztof Szalewicz
1Department of Physics and Astronomy, University of Delaware, Newark, Delaware 19716, USA. konpat@gmail.com
The Journal of Chemical Physics
|September 14, 2010
Summary
A new ab initio potential for argon dimer interactions was developed using advanced coupled-cluster theory. This accurate potential refines understanding of interatomic forces in noble gases.
Area of Science:
- * Physical Chemistry
- * Computational Quantum Chemistry
Background:
- * Accurate interatomic potentials are crucial for understanding noble gas behavior.
- * Previous argon dimer potentials had limitations in accuracy and basis set size.
Purpose of the Study:
- * To develop a highly accurate ab initio interaction potential for the electronic ground state of argon dimer (Ar2).
- * To rigorously investigate the convergence of coupled-cluster calculations with respect to basis set size and excitation levels.
Main Methods:
- * Employed coupled-cluster theory up to quadruple excitations (CCSDTQ).
- * Utilized large, optimized basis sets, including septuple(sextuple)-zeta levels, with optimized diffuse functions.
- * Performed complete basis set extrapolations and analyzed convergence patterns.
Main Results:
- * Developed a new ab initio potential for Ar2, significantly more accurate than previous ones.
- * Identified basis sets in literature that yield qualitatively incorrect results for corrections.
- * Interaction energy at near-minimum distance: -99.291±0.32 cm⁻¹.
- * Analytic potential predicts a minimum well depth of 99.351 cm⁻¹ at 3.762 Å.
Conclusions:
- * The developed potential represents the most accurate argon-argon interaction to date.
- * High-level correlation effects do not always converge faster than lower-level effects.
- * Emphasizes the importance of large basis sets and careful convergence analysis for accurate potentials.
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