Molecular dynamics simulation of organic materials: structure, potentials and the MiCMoS computer platform

Abstract

The science of organic crystals and materials has seen in a few decades a spectacular improvement from taking months for an X-ray structure determination to minutes and from single-point lattice energy calculations to dynamic simulations of hundreds of thousands of atoms. While diffraction experiments now proceed in a compact, almost tabletop apparatus, theoretical chemistry is performed in comprehensive computer program environments that encode each particular way of modeling solid-state physics. Extremely fast experimental and theoretical advances expand the limits of what was thought possible just a few years ago, in search of new useful materials while shedding light on their complex nanoscale properties to an unprecedented degree of accuracy. In materials science theory, the undisputed leader is molecular dynamics simulation, which provides a detailed picture of molecular events at atomic lengths and timescales. This highlight traces a bit of history, clarifies a few fundamental points, and then illustrates the capabilities of a molecular simulation platform recently developed at the Chemistry Department of the Università degli Studi di Milano (Unimi), with high performance intermolecular potentials and case studies of large amplitude rotational diffusion, of the stability of crystalline clusters, and of anisotropic treatment of mechanical properties.