The Journal of Chemical Physics

Effect of electron correlation on the H2CO-He interaction potential

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A previously reported Hartree-Fock (HF) interaction potential between H2CO(1A1) and He(1S) is modified through a series of configuration interaction (CI) calculations. The CI contribution is described by a three-term (l = 0,1,2) Legendre polynomial expansion in the angle θ formed by the direction of incidence of He and the CO bond of formaldehyde. No significant azimuthal angle dependence is obtained. Correlation is found to have little effect in the strongly anisotropic repulsive region of the interaction potential but dominates the well and long-range regions. The maximum well depth is attained for in-plane approaches of He and lies in the range 35-40°K for arbitrary θ at center of mass separation of 7.5 a.u. The CI contribution in the region of the minimum is believed accurate to ∼20%. Copyright © 1975 American Institute of Physics.