Prediction of mineral crystal structures

The aim of our work has been to develop a computer simulation technique that can predict the structure of minerals. The basis of the technique is energy minimisation, i.e. all structural parameters are varied until the configuration with the lowest lattice energy is achieved; the initial configuration usually corresponds to an “ideal” structure based on regular polyhedra. The lattice energy is calculated using a specified potential model which includes electrostatic and short-range terms. These techniques can be applied to two distinct areas of structure prediction. The first concerns discrimination between alternative space groups proposed for the same structure. The second concerns the calculation of distortions from ideal close-packed structures. Here we concentrated mainly on silicate minerals. Furthermore, by varying the cell parameters we were able to simulate the effect of pressure on the crystal structure. Our results show that it is possible to establish potential models which predict detailed features of mineral structural chemistry.