Quantum rotational scattering of H2 and its isotopologues with He

Quantum close-coupling computations of the rotational quenching of H2 and its isotopologues due to He impact are performed using a highly accurate potential energy surface. State-to-state cross sections are obtained in a wide range of collision energies between 10−5 cm−1 and 104 cm−1, and the theoretical rate coefficients are reported for temperatures ranging from 10−4 K to 3000 K. Compared with previous studies, the well depth of the potential adopted in this study is larger, leading to stronger resonance effects in the cross sections of He-HD. The accurate potential was employed to investigate the isotope effects of H2 in detail. The cross-section resonances shift towards lower collision energies and become stronger with increasing reduced mass. The calculated cross sections and rate coefficients of H2 and its isotopic variants in collisions with He are provided to study the energy transfer in these systems.