PyQCAMS: Python Quasi-Classical Atom–Molecule Scattering

We present Python Quasi-classical atom–molecule scattering (PyQCAMS v0.1.0), a new Python package for atom–diatom scattering within the quasi-classical trajectory approach. The input consists of the mass, collision energy, impact parameter, and pair-wise/three-body interactions. As the output, the code provides the vibrational quenching, dissociation, and reactive cross sections along with the rovibrational energy distribution of the reaction products. We benchmark the program for a reaction involving a molecular ion in a high-density ultracold gas, RbBa⁺ + Rb. Furthermore, we treat H₂ + Ca → CaH + H reactions as a prototypical example to illustrate the properties and performance of the software. Finally, we study the parallelization performance of the code by looking into the speedup of the program as a function of the number of CPUs used.