Improved potential energy surface for He–CO2

Abstract

The anisotropic potential energy surface of He–CO2 is determined by the simultaneous analysis of newly measured high resolution total differential cross sections, differential energy loss spectra, new low temperature second virial coefficients, new diffusion, and viscosity data. The calculations are carried out in the infinite-order-sudden approximation. The repulsive anisotropy of the potential is determined from the rotationally inelastic cross sections and the quenching of the diffraction oscillations, while the absolute scale is fixed by the position of these oscillations. The second virial coefficient data are essentially sensitive to the general features of the spherical effective potential well. The transport data are then correctly predicted by this potential surface which differs both in the anisotropy and the spherical part from the recently derived multiproperty fit potential for this system.

Experimental He-pressure broadening for the R(10) and P(2) lines in the ν3 band of 13CO2, and experimental pressure shifts for R(10) measured at several temperatures between 300K and 100K

“…Here and in the following, we use c He = c( 13 CO 2 -He) for simplicity. We found a value equal to 0.648 ± 0.001 for n R(10) and equal to 0.690 ± 0.004 for n P (2) . These values are close to the mean value found by Brownsword et al [ Tables 4 and 5 and are plotted in Fig.…”

“…The complexes of CO 2 with rare gas atoms represent a very interesting intermediate case between the semi-rigid and nearly free internal rotor limits. Several empirical [2] and ab initio [3][4][5] intermolecular potential energy surfaces (PESs) have been published for the He-CO 2 system. Some of these PESs present salient differences for the attractive part of the intermolecular potential.…”

“…The intermolecular interaction between carbon dioxide (CO 2 ) and helium (He) has been extensively studied from a theoretical point of view [1][2][3] due to the role of this rather simple system as a fundamental reference system for empirical and ab initio determination of intermolecular forces. The complexes of CO 2 with rare gas atoms represent a very interesting intermediate case between the semi-rigid and nearly free internal rotor limits.…”

A new ab initio potential energy surface and infrared spectra for the Ne–CS2 complex

“…At the same time, some theoretical researches have performed the construction of the ab initio potential energy surface (IPES) and the calculation of the rovibrational energy levels. In the previous theoretical calculations [9][10][11][12][13][14][15][16][17], ab initio PES were obtained by assuming the CO 2 monomer as a rigid rotor, which is not sufficient for describing infrared spectra as the transition in the intramolecular vibrational mode is usually involved [25,26]. One effective way is to take into account the influence of intramolecular vibrational mode on the potential energy surface and dynamical calculations [27,28].…”

“…Such studies taking into account of discrete spectra can greatly enhance our understanding on the intermolecular potentials and dynamics of these weakly bound molecules. Carbon dioxide complexes have been completely investigated experimentally [1][2][3][4][5][6][7][8] and theoretically [9][10][11][12][13][14][15][16][17][18][19][20][21][22][23], since CO 2 is one of the most significant absorbers of infrared radiation in the earth's atmosphere and interstellar chemistry. As an analog of CO 2 , carbon disulfide is also intriguing because sulfur itself is a key element at the ground level of our atmosphere [24].…”