Quantum scattering of KCl with He/para- H 2 $\mbox{H}_{2}$ : potential energy surface and rate coefficients at low temperature

Abstract

We present new two- and four-dimensional potential energy surfaces for the KCl( $\mbox{X}^{1} \varSigma ^{+}$ )-He and KCl( $\mbox{X}^{1} \varSigma ^{+}$ )-para-H2 systems calculated with the internuclear distances of KCl and H2 frozen at their experimental minimum energy. The CCSD(T) level of theory with aug-cc-pVQZ/AQZP basis sets is used. The potential surfaces present well depths of about $78~\mbox{cm}^{-1}$ and $235~\mbox{cm}^{-1}$ below the dissociation limit of the above interacting systems respectively. With these potential surfaces, cross sections are obtained in the close coupling scheme and rate coefficients inferred by averaging the cross sections over a Maxwell-Boltzmann velocity distribution for temperature below 50 K. A propensity towards $\Delta J = 1$ transitions is observed.