Quantum dynamics of vibration–vibration energy transfer for vibrationally excited HF colliding with H₂

Abstract

The rate constants for H 2 -HF energy transfer processes, especially for those in vibrationally excited states, are very demanding in astrophysics and chemical laser engineering, especially for those in vibrationally excited states. Based on our recent potential energy surface, we used the coupled-states approximation including the nearest neighboring Coriolis couplings with energy-based local basis set to perform dynamics calculation for the H 2 -HF energy transfer system. Rate constants for vibrational transitions (1; 3) ! (0; 4), (1; 3) ! (2; 2), and (0; 3) ! (1; 2) were obtained. For state-to-state rate constants, transitions that have no internal angular momentum gap dominate at high temperatures. The vibrational-resolved rate constant for (1; 3) ! (0; 4) initially decreases and then increases with the temperature, while those for (1; 3) ! (2; 2), and (0; 3) ! (1; 2) transitions monotonically increase. The calculated rate constants are in good agreement with the available experimental results. These dynamical data can be further applied to the numerical simulation of hydrogen fluoride chemical laser.

Breakdown of energy transfer gap laws revealed by full-dimensional quantum scattering between HF molecules

“…The Hamiltonian is defined in diatom–diatom Jacobi coordinates and the scattering matrix ( S -matrix) elements for a given set of total angular momentum ( J ) and parities are computed in the body-fixed frame using a log-derivative method 50,51 . The validity of CSA–NNCC approach has been demonstrated for the H 2 –H 2 /HD 39 , and H 2 –HF 39,52 systems, and in SI for the current system as well. The use of this approximation reduces the size of the system to J max /3, which makes such calculations possible.…”

Quantitatively Determining Surface–Adsorbate Properties from Vibrational Spectroscopy with Interpretable Machine Learning

“…Our results (Figure S11 and Table S3) suggest that it is possible to learn hidden information with satisfying accuracy regarding low frequency modes by collecting full information of high frequency modes and analyzing it using ML. Note that this approach is distinct with probing vibration−vibration coupling, which would require more advanced tools such as quantum dynamics 32 or even full quantum state analysis. 33 The importance of this new approach is distinguishable.…”

Quantum Dynamics of Rotational Energy Transfer Processes for N2–HF and N2–DF Systems

“…As shown in Figure a, the transition of (6, 0) → (4, 1) has an absolute dominance in this series, which contributes roughly two-thirds of the total rotational quenching rate coefficients of (6, 0). As a well-known mechanism in energy transfer, the energy gap law, , in which the most dominant inelastic transitions are the ones with the smallest energy gaps between the initial and final CMSs of the collision partners, was successfully applied to explain the propensities in many systems, such as H 2 –HF, , H 2 –CO, and Ar–HF . The energy difference between the initial CMS (6, 0) and the final CMS (4, 1) is −2.6 cm –1 , which is the smallest one of all inelastic collisional channels.…”

“…Recently, the CSA was improved by Xie et al by including the nearest neighbor Coriolis couplings (NNCC), which reduces significantly the computational cost without a major loss of accuracy. The CSA–NNCC approach has already been successfully applied to H 2 –H 2 /HD, H 2 –HF, , D 2 –HF, and HF–HF systems. As pointed out by corresponding experiments, ,− the vibrational energy transfers are much more inefficient than the rotational ones.…”