ABSTRACT
Quantum-level density functional simulations of planar graphene subjected to mechanical strains are found to develop monoclinic or nearly-orthorhombic crystal structures through second-order phase transitions. They are achieved through a bond rotation similar in part to the Stone-Wales transformation. The key result is the observation of the rotation in even the smallest primitive cell, which connects to the transformation through the space-filling crystal concept. Contrary to earlier observations of phase change in graphene, the deformations needed to obtain the configurations exhibit both kinetic and thermodynamic features.