Computer modelling of complex molecular ionic materials

Molecular ionic materials present a considerable challenge in computer modelling because any potential model employed must accommodate both ionic and covalent forces. This paper will describe how energy minimisation and molecular dynamics techniques have been used to model a series of these materials. Results will be presented of calculations of structural and lattice properties of alkali metal nitrates, ammonium halides and of two phases of ammonium nitrate. It will be shown that such complex materials can be reliably simulated by relative simple potential models, provided both ionic and covalent interactions, and the balance between them, are correctly represented.