Modeling of Energy Transfer From Vibrationally Excited CO sub(2) Molecules: Cross Sections and Probabilities for Kinetic Modeling of Atmospheres, Flows, and Plasmas

• Published in: The journal of physical chemistry. A, Molecules, spectroscopy, kinetics, environment, & general theory Vol. 117; no. 45; pp. 11430 - 11440-11430-11440
• Main Authors: Lombardi, Andrea, Faginas-Lago, Noelia, Pacifici, Leonardo, Costantini, Alessandro
• Format: Journal Article
• Language: English
• Published: 04-01-2013
• Subjects: Cross sections; Energy distribution; Exchange; Excitation; Mathematical models; Plasmas; Potential energy; Rotational
• ISSN: 1089-5639; 1520-5215
• DOI: 10.1021/jp408522m

We present extended applications of an established theoretical and computational machinery suitable for the study of the dynamics of CO sub(2)+CO sub(2) collisions, focusing on vibrational energy exchange, considered over a wide range of energies and rotational temperatures. Calculations are based on quasi-classical trajectories on a potential energy function (a critical component of dynamics simulations), tailored to accurately describe the intermolecular interactions, modeled by the recently proposed bond-bond semiempirical formulation that allows the colliding molecules to be stretchable, rather than frozen at their equilibrium geometry. In a previous work, the same potential energy surface has been used to show that modifications in the geometry (and in physical properties such as polarizability and charge distribution) of the colliding partners affect the intermolecular interaction and determine the features of the energy exchange, to a large extent driven by long-range forces. As initial partitioning of the energy among the molecular degrees of freedom, we consider the excitation of the vibrational bending mode, assuming an initial rotational distribution and a rotational temperature. The role of the vibrational angular momentum is also carefully assessed. Results are obtained by portable implementations of this approach in a Grid-computing framework and on high performance platforms. Cross sections are basic ingredients to obtain rate constants of use in advanced state-to-state kinetic models, under equilibrium or nonequilibrium conditions, and this approach is suitable for gas dynamics applications to plasmas and modeling of hypersonic flows.