Using constant-pressure ab initio molecular dynamics we have simulated the conversion of carbon from graphite to diamond under high pressure. We found that the transformation path proceeds through sliding of graphite planes into an unusual orthorhombic stacking, from which an abrupt collapse and buckling of the planes leads to both cubic and hexagonal forms of diamond in comparable proportions. The mutual orientation of the initial and final phases is in agreement with that of shock-wave experiments.

• Received 13 December 1994

DOI:https://doi.org/10.1103/PhysRevLett.74.4015