posted on 2016-01-07, 00:00authored byA. A. Sycheva, G. G. Balint-Kurti, A. P. Palov
The
interatomic potentials of the a2Π and b2Π states of the OAr+ molecule are calculated
using the relativistic complete-active space Hartree–Fock method
followed by a multireference configuration interaction calculation
with an aug-cc-pwCVNZ-DK basis sets where N is 4 and 5. The calculations
were followed by an extrapolation to the complete basis set limit.
An avoided crossing between the two potential energy curves is found
at an internuclear separation of 5.75 bohr (3.04 Å). As the transition
probability between the curves is negligible in the relative collision
energy range 0.03–500 eV of interest here, collisions on the
lower adiabatic a2Π potential may be treated without
reference to the upper state. For low energies and orbital angular
momentum quantum numbers, the one-dimensional radial Schrödinger
equation is solved numerically using a Numerov algorithm method to
determine the phase shift. The semiclassical JWKB approximation was
employed for relative energies greater than 5 eV and orbital angular
quantum numbers higher than 500. Differential, integral, transport
(diffusion), and viscosity cross sections for elastic collisions of
oxygen atoms with argon ions are calculated for the first time for
the range of relative collision energies studied. The calculated cross
sections are expected to be of utility in the fields of nanotechnology
and arc welding. The combination of an Ar+(2P) ion and a O(3P) atom gives rise to a total of 12 different
molecular electronic states that are all coupled by spin–orbit
interactions. Potential energy curves for all 12 states are computed
at the complete active space self-consistent field (CASSCF) level
and scattering calculations performed. The results are compared with
those obtained using just the lowest potential energy curve.