First principles prediction of crystal structures of CO 2

Abstract

Structures of CO2 molecular crystals were predicted completely from first principles. The geometry and partial charges of a CO2 molecule were determined by ab initio molecular orbital MP2 calculations. The intermolecular potential functions employed here were determined to reproduce the intermolecular interaction energies obtained by ab initio molecular orbital calculations at the MP2/6-311G(3d) level for CO2 dimers. Then, the crystal structure has been searched for as the most energetically stable packing for an eight-molecule system under a periodic boundary condition, without any information on the space group symmetry or the lattice constants. The thus predicted crystal structures for low and high pressure phases coincide well with the observed ones. Thus, we have succeeded in breaking ground in predicting molecular crystal structures from first principles, i.e. only from the chemical formula of the CO2 molecule. (C) 1997 by John Wiley & Sons, Ltd.