Global potential energy surface for the O2 + N2 interaction. Applications to the collisional, spectroscopic, and thermodynamic properties of the complex

A detailed characterization of the interaction between the most abundant molecules in air is important for the understanding of a variety of phenomena in atmospherical science. A completely {\em ab initio} global potential energy surface (PES) for the O$_2(^3\Sigma^-_g)$ + N$_2(^1\Sigma^+_g)$ interaction is reported for the first time. It has been obtained with the symmetry-adapted perturbation theory utilizing a density functional description of monomers [SAPT(DFT)] extended to treat the interaction involving high-spin open-shell complexes. The computed interaction energies of the complex are in a good agreement with those obtained by using the spin-restricted coupled cluster methodology with singles, doubles and noniterative triple excitations [RCCSD(T)]. A spherical harmonics expansion containing a large number of terms due to the anisotropy of the interaction has been built from the {\em ab initio} data. The radial coefficients of the expansion are matched in the long range with the analytical functions based on the recent {\em ab initio} calculations of the electric properties of the monomers [M. Bartolomei et al., J. Comp. Chem., {\bf 32}, 279 (2011)]. The PES is tested against the second virial coefficient $B(T)$ data and the integral cross sections measured with rotationally hot effusive beams, leading in both cases to a very good agreement. The first bound states of the complex have been computed and relevant spectroscopic features of the interacting complex are reported. A comparison with a previous experimentally derived PES is also provided

Surfaces d'énergie potentielle pour la dynamique : cas de l'interaction C(3P)+OH(X2Pi)

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Intramolecular dependence of the frequency dependent polarizabilities of Li2(a 3Σu+) and Na2(a 3Σu+) and van der Waals dispersion coefficients for atom-diatom and diatom-diatom alkali dimers

cited By 16International audienceAn ab initio time dependent gauge invariant method (TDGI) has been used to compute the frequency dependent dipole and quadrupole polarizabilities of Li, Na, Li2(a 3∑u+) and Na2(a 3∑u+) and their dependence on the internuclear distance of the diatomic species. The dependence of the isotropic and anisotropic components of the static dipole polarizabilities on the diatomic distance was fitted to an analytical form which has an asymptotic form in agreement with the theoretical expression derived by Heijmen, T. G. A., Moszynski, R., Wormer, P. E. S., and van der Avoird, A., Molec. Phys., 89, 81. Long range two-body C6 coefficients have been evaluated for all combinations of atom-atom, atom-homonuclear diatom and homonuclear diatom-homonuclear diatom systems in which the diatomics are in the a 3∑u+ state. Furthermore, the C8 coefficients for the atom-atom and atom-diatom interactions and the three-body C9 coefficients for the four atom-diatom systems have been obtained. For the atom-diatom case, the dipole-induced dipole C6 coefficients have been calculated for various diatomic distances up to 15 Å. The distance dependence of their isotropic C6000 and anisotropic C6202 components has been fitted to an analytical form similar to that used for the static dipole polarizabilities of the diatomics