Numerical comparison between electronically adiabatic and diabatic representations for collinear atom–diatom collisions

Abstract

Within the framework of quantum coupled‐channel calculations on nonreactive atom–diatom collision systems involving two electronic potential surfaces, we test the electronically adiabatic representation obtained within the diatomics‐in‐molecules approximation against a similarly derived diabatic representation. The testing is numerical, with a view toward establishing computational advantages of one representation over the other with regard to (a) convergence of computed probability as the diatomic molecular basis is expanded; (b) convergence with respect to the starting position of the numerical integration; (c) convergence with respect to the distance between stabilizations; and (d) convergence with respect to the integration steplength. The adiabatic representation shows definite advantages in tests (a) and (b), but they are not sufficient to offset the much more rapid execution time possible with the diabatic basis. The significance of these results is discussed.