Mode-specific quasi-classical dynamics of the F− + SiH3Cl system

Abstract

We conducted mode-specific quasi-classical trajectory (QCT) simulations of the gas-phase F⁻ + SiH₃Cl reaction employing a full-dimensional, coupled-cluster-quality potential energy surface. Simulations were performed at collision energies ranging from 1 to 40 kcal mol⁻¹, with one vibrational quantum selectively excited in each of the six distinct vibrational modes of SiH₃Cl, namely the SiCl stretching, SiH₃ rocking, SiH₃ umbrella and deformation modes, and symmetric and asymmetric SiH stretching. Multiple reaction channels were analyzed, including chloride-ion substitution via inversion and retention pathways, proton abstraction, hydrogen chloride (HCl) formation, hydride-ion substitution, molecular-hydrogen production, and FHCl⁻ formation. From the QCT simulations, reaction probabilities, integral cross sections, initial attack angle and scattering angle distributions, and product energy distributions (internal, translational, vibrational, and rotational) were derived. Notably, excitation of SiH stretching modes led to a modest reduction in cross sections for chloride-ion substitution, whereas other product channels showed mild to significant enhancements. Excitation of other vibrational modes minimally impacted chloride-substitution and proton-abstraction cross sections, but significantly, although less markedly than SiH stretching modes, enhanced the remaining product channels. The initial attack angle and scattering angle distributions are not affected by vibrational excitations for all product channels, and the post-reaction energy distributions showed minimal effects.