Ab initio potential energy surface, infrared spectrum, and second virial coefficient of the He–CO complex

Abstract

Symmetry-adapted perturbation theory has been applied to compute the intermolecular potential energy surface of the H e-C O complex. The interaction energy is found to be dominated by the first-order exchange contribution and the dispersion energy. The ab initio potential has a single minimum of em = -24.895 cm " 1 for the linear C O -H e geometry at Rm = 6.85 bohr. The computed potential energy surface has been analytically fitted and used in converged variational calculations to generate bound rovibrational states of the H e-C O molecule and the infrared spectrum, which corresponds to the simultaneous excitation of vibration and internal rotation in the CO subunit within the complex. The predicted positions and intensities of lines in the infrared spectrum are in good agreement with the experimental spectrum [C.E. Chuaqui et al., J. Chem. Phys. 101, 39 (1994)]. The theoretical potential was also checked by comparison of computed excess second virial coefficients with the experimental data. The ab initio interaction virial coefficients, including quantum corrections, lie within the experimental error bars over a wide range of temperatures.

Ro-vibrational quenching of CO (v = 1) by He impact in a broad range of temperatures: A benchmark study using mixed quantum/classical inelastic scattering theory

“…[9][10][11][12]28 The improvement of detection techniques 29,30 and development of the PES [31][32][33] went through several refinement cycles. Finally, an acceptable agreement between theory and experiment has been reached in different parts of the desired broad range of temperatures.…”

Investigation of the CH3CN-CO2 Potential Energy Surface (PES) Using Symmetry-Adapted Perturbation Theory (SAPT)

“…The total interaction energy in the present work will then be approximated by combining equation (6) and equation (8) to give…”

“…This can lead to significant physical insight about the interaction in contrast to the currently more popular supermolecular (SM) method which returns only a single number. SAPT has been used to successfully investigate a variety of systems including Ar-H 2 [6],He-HF [7],He-CO [8], Ar-HF [9], He-C 2 H 2 [10], H 2 -CO [11], and(H 2 0) 2 [12].…”

“…The HF Interaction Energy E^t and Its Components According to Equation (8) Shown as a Function of ßj for R = 4.75 Ä 37 vn…”

Rotational energy transfer in collisions between CO and Ar at temperatures from 293 to 30 K

“…Understanding these long-range forces is essential to calculating many properties of gases [1][2][3][4]. A reliable potential energy surface describing these intermolecular forces can be used to calculate bulk properties of gases including viscosity, diffusion, thermal conductivity, and virial coefficients [5][6][7][8][9]. These long-range forces also influence pressure broadening of spectra; larger van der Waals forces generally lead to more broadening.…”