Vibrational Energy Transfer in CO+N2 Collisions: A Database for V–V and V–T/R Quantum-Classical Rate Coefficients

Abstract

Knowledge of energy exchange rate constants in inelastic collisions is critically required for accurate characterization and simulation of several processes in gaseous environments, including planetary atmospheres, plasma, combustion, etc. Determination of these rate constants requires accurate potential energy surfaces (PESs) that describe in detail the full interaction region space and the use of collision dynamics methods capable of including the most relevant quantum effects. In this work, we produce an extensive collection of vibration-to-vibration (V–V) and vibration-to-translation/rotation (V–T/R) energy transfer rate coefficients for collisions between CO and N2 molecules using a mixed quantum-classical method and a recently introduced (A. Lombardi, F. Pirani, M. Bartolomei, C. Coletti, and A. Laganà, Frontiers in chemistry, 7, 309 (2019)) analytical PES, critically revised to improve its performance against ab initio and experimental data of different sources. The present database gives a good agreement with available experimental values of V–V rate coefficients and covers an unprecedented number of transitions and a wide range of temperatures. Furthermore, this is the first database of V–T/R rate coefficients for the title collisions. These processes are shown to often be the most probable ones at high temperatures and/or for highly excited molecules, such conditions being relevant in the modeling of hypersonic flows, plasma, and aerospace applications.

Improved Quantum–Classical Treatment of N2–N2 Inelastic Collisions: Effect of the Potentials and Complete Rate Coefficient Data Sets

“…, the intramolecular potential) of the diatom. In the previous MQC calculations, − ,, the diatomic intramolecular potential was described by the empirical Morse potential, so the analytical solutions (eigenvalues and eigenfunctions) of eq can be obtained analytically and were directly adopted in the calculation. In this paper, to consider any kind of diatomic intramolecular potential, eq is solved numerically by the subroutine SCHRQ of the well-known program LEVEL developed by Le Roy .…”

“…For the expansion coefficients [amplitudes for the inelastic processes N 2 ( v 1 ) + N 2 ( v 2 ) → N 2 ( v 1 ′) + N 2 ( v 2 ′ ) in this paper], we plug the expansion into the time-dependent Schrödinger equation and obtain the following set of coupled equations where in which V is the intermolecular potential of the colliding system. is called the matrix coupling element and is obtained by numerical integration based on the eigenfunction of eq . Note that in the original MQC calculations, − ,, is integrated analytically using the Morse wave function.…”

“…The procedure described above was used to calculate V−T/R and V−V coefficients for processes (1), ( 2), (3), and (4) at various v initial quantum numbers with gaps of 1 or 2 quantum numbers, and the source data are reported in the Zenodo repository 51 as black values. Then GPR models were employed for rate coefficient predictions for the missing quantum numbers v in the whole temperature range, and the predicted data are reported 51 as green values.…”

“…In the last years, we tackled this problem by using a combined strategy consisting of the application of a mixed quantum–classical (MQC) dynamics method, allowing the quantum description of molecular vibrations and rotational–vibrational coupling, and a classical representation of the remaining degrees of freedom, and an analytical nonreactive PES, built according to the improved Lennard-Jones (ILJ) model . We were able to produce large tables and data sets of vibration-to-vibration (V–V) and vibration-to-translation/rotation (V–T/R) rate coefficients in a wide temperature range for a variety of systems, − covering many initial vibrational states of the colliding dimers, not too close to the dissociation limit. The latter choice is because the MQC method is based on an internally consistent use of a Morse-like intramolecular potential and a corresponding Morse-like vibrational wave function, which are known to be deficient for the representation of highly excited states.…”

The dawn of hydrogen and halogen bonds and their crucial role in collisional processes probing long-range intermolecular interactions

“…13–15 Such forces also drive the dynamics of elementary energy transfer processes, as these promoting vibration–vibration, vibration–rotation, vibration–translation, and vibration–electronic transitions occur in the gas phase, in plasmas, and at gas–liquid and gas–surface inter-phases. 16–20…”