We present new ab initio calculations of the interaction potential and the elastic and inelastic cross sections for He scattering by I2. The electronic structure calculations of the interaction potential are based on an extensive one-electron basis set (triple zeta plus a d set on each I, an s function plus a p set at the I2 bond center, and quadruple zeta plus two p sets on He), a two-configuration-SCF orbital set, and a configuration interaction calculation based on all single and double excitations out of the two-configuration reference space. The calculations are performed at 16He-I2 distances for nine combinations of I2 vibrational displacement and orientation. A new form of analytic representation is presented that is particularly well suited to efficient and accurate fitting of ab initio interaction potentials that include vibrational displacements. Scattering calculations are performed by the vibrational close-coupling, rotational-infinite-order-sudden approximation with a converged vibrational basis.
- Multireference configuration interaction calculations
- Nonpairwise additive potential surface
- Vibrational-rotational scattering calculations