Solvation of Fluoroform in Liquid Krypton: A Theoretical Cryospectroscopy Approach on a HPC Environment

Abstract

The anharmonic CH stretching vibrational frequency was calculated for a dilute solution of fluoroform (CF\(_3\)H) in liquid krypton at 131 K from classical Monte Carlo (MC) simulations followed by electronic structure calculations (at various levels of theory, including B3LYP, MP2 etc.) for small clusters including fluoroform and few solvent atoms residing in its neighborhood. Nuclear dynamics calculations were also quantum mechanical, i.e. the vibrational Schrodinger equation was solved at grid of points representing an intersection through the vibrational potential energy surface of fluoroform, corresponding to the CH stretching motion. The calculated Raman bands are compared with experimental results, and an in-depth physical insight is gained into the factors influencing the CH stretching frequency shifts upon solvation. On the basis of Kitaura-Morokuma and RVS SCF analysis of the vibrational potentials, it was concluded that the solvent electrostatics influence (both classical and non-classical) would induce frequency red shifts, while the exchange Pauli repulsion induces frequency blue shifts. This robust and complex computational methodology was implemented in a HPC environment.