Weak intermolecular interactions: Statics and dynamics

Abstract

AbstractThis contribution consists of four parts: energy calculations, physical (mainly spectroscopic) characteristics, and static and dynamic aspects of interactions leading to the formation of van der Waals species.The main, first, part includes specific comments on computational procedures for systems of different size ([number of atoms, number of electrons]: small [4, 10], medium [dozens, hundreds], large [103, 104]) and colloid systems (considering also supermolecular structures). Rigorous and simplified methods of molecular quantum mechanics can be used with the first and second groups, respectively; for larger systems, only empirical potentials and the methods of the physics of a continuum are available. The transferability of empirical potential parameters is critically examined. The role of temperature, Gibbs energy, and entropy is mentioned together with the ensemble theory. The search for stationary points on potential energy surfaces (PES) and analytical fits to PES are reviewed briefly.The second part is an outline of what is expected from computational chemistry to meet the needs of spectroscopists. The third section deals with selection rules, equilibria and the rates of processes involving van der Waals species, and the role of these species in common chemical reactivity. The crucial role of entropy is mentioned in connection with hydrophobic phenomena, entropy‐driven processes, and partitioning of substances between water and a nonpolar phase.In the final section, the role of computer experiments (molecular dynamics, Monte Carlo) is pointed out. Some shortcomings and promising features of these techniques are summarized.