Hypothetical crystal structures of benzene at 0 and 30 kbar

Possible crystal structures of benzene were generated without any prior crystallographic information, using a systematic grid search method. Only structures with one molecule in the asymmetric unit were considered. 31 space groups were investigated, and the resulting structures were clustered and checked for stability upon removal of the space-group symmetry. In the enthalpy range similar to 10 kJ mol(-1) 30 structures were found at zero pressure and 20 structures at a pressure of 30 kbar. Their pressure-dependent rankings and interconversions are discussed. The results are compared to previous, less complete, investigations. A possible structure for the high-pressure phase benzene (II), on which only limited powder diffraction data have been published, is suggested.