Py3BR: Three-Body Recombination in Python*

Three-body recombination reactions, in which three free atoms collide to form a molecule and a free atom, play a crucial role in a multitude of scenarios in chemical physics [1,2]. We present Python 3-Body Recombination (Py3BR), an open-source program dedicated to studying these reactions and computing three-body recombination rate coefficients for atom-atom-atom and ion-atom-atom systems. Py3BR is based on a classical trajectory method in hyperspherical coordinates which maps the three-body problem to a single particle in a 6-dimensional space, a method that has shown to agree well with experiment [3,4]. Results are presented for an atom-atom-atom system (P + He + He) and an ion-atom-atom system (Sr­⁺ + Cs + Cs).

[1] J. Pérez-Ríos, An Introduction to Cold and Ultracold Chemistry (Springer International Publishing, New York, 2020).

[2] M. Mirahmadi & J. Pérez-Ríos (2022) Three-body recombination in physical chemistry, International Reviews in Physical Chemistry, 41:3-4, 233-267, DOI: 10.1080/0144235X.2023.2237300

[3] Mirahmadi M, Pérez-Ríos J, Egorov O, Tyuterev V, Kokoouline V. Ozone formation in ternary collisions: Theory and experiment reconciled. Physical Review Letters 2022; 128(10): 108501.

[4] Pérez-Ríos J, Greene CH. Universal temperature dependence of the ion-neutral-neutral three-body recombination rate. Physical Review A 2018; 98(6): 062707