The structures of organic molecules in crystals: simulations using the electrostatic potential

Studies devoted to simulations of crystal lattice effects on the electronic and spatial structures of organic molecules in molecular crystals with inclusion of the external potential created by the crystal environment into the Hamiltonian of the isolated molecule are surveyed. Various methods for the representation of the charge distribution in a molecule by atomic point charges or multipoles are compared and the necessity of the empirical correction of the molecular electrostatic potential obtained using the Hartree–Fock and semiempirical calculations is substantiated. The procedures for the modification of the Hamiltonian are analysed. The limits of applicability of this approach to simulations of specific intermolecular interactions (hydrogen bonds) are discussed. Examples of the use of methods based on the application of the electrostatic potential in the calculation of the crystal lattice energy, simulations of the molecular conformations in crystals and electronic excitations are presented. The importance of the results of computation of the electronic structures of molecules in crystals for systematisation of the crystal structures and, in particular, for comparative analysis of the structures of polymorph modifications is demonstrated.