Photodissociation of the methane–argon complex. I. Ab initio intermolecular potential depending on the methane vibrational coordinates.

We calculated the intermolecular potential for the complex methane-Ar in which the methane is deformed along the ν[sub 1] and the ν[sub 3] vibrational normal modes. We present a fit of the potential energy surface as a function of the three argon coordinates and the four normal mode coordinates q[sub ν][sub 3x], q[sub ν][sub 3y], q[sub ν][sub 3z], and q[sub ν][sub 1]. This potential is used in the following paper [J. Chem. Phys. 117, 7562 (2002)] dealing with the calculation of the lifetimes of the quasibound states of the dimer with the methane monomer in the vibrationally excited ν[sub 3] state. [ABSTRACT FROM AUTHOR]