Atomic and molecular physics

Comparison of ab initio and Lennard-Jones interaction potentials and their effect on particles beam scattering

S. A. Nikitenko^a, L. A. Varshavchik^a, Z. G. Lullin^b, D. D. Galitsyn^a, E. A. Starovoitov^a, V. A. Bocharnikov^a, E. E. Mukhin<sup>a

a</sup> Ioffe Institute, St. Petersburg
^b Saint Petersburg Electrotechnical University "LETI"

Abstract: The classical Lennard-Jones interaction potential was compared with ab initio potentials computed using the NWChem software. The ab initio calculations were performed using the MP2, CCSD and CCSD(T) methods with the following extrapolation to complete basis set limit. The resulting potentials were used to simulate the scattering of a boron atom beam in argon and helium gases using the KITe code. The elastic scattering angles, total and effective cross sections, as well as the scattering behavior of the atoms beam were compared for the different interatomic potentials. It was demonstrated that the Lennard-Jones potential, which is computationally much simpler than the accurate ab initio potential, exhibits deviations in the potential well and the repulsive regions. When scattering the model beam, atoms lose energy more rapidly with the Lennard-Jones potential than with the ab initio potential, although the shapes of the particle fronts are quite similar. The results of this work provide arguments for selecting an appropriate interatomic potential for elastic scattering modeling depending on the specific problem.

Keywords: NWChem, KITe, interatomic potential, ab initio, Lennard-Jones potential, elastic scattering, Monte-Carlo.

Received: 07.04.2025
Revised: 12.05.2025
Accepted: 13.05.2025

DOI: 10.61011/JTF.2025.11.61591.55-25

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