Topography of potential-energy surfaces for Van der Waals complexes

The recently developed program ORIENT 3 is applied to several complexes including acetonitrile dimer, benzene–water, benzene–ammonia and chlorine dimer. We employ distributed multipole analysis in conjunction with the eigenvector-following optimization technique to calculate minima, saddle points and rearrangement pathways. The potential-energy surface of the chlorine dimer is investigated as an example of anisotropic repulsion.