Temperature-accelerated method for exploring polymorphism in molecular crystals based on free energy

Phys Rev Lett. 2011 Jul 1;107(1):015701. doi: 10.1103/PhysRevLett.107.015701. Epub 2011 Jun 29.


The ability of certain organic molecules to form multiple crystal structures, known as polymorphism, has important ramifications for pharmaceuticals and high energy materials. Here, we introduce an efficient molecular dynamics method for rapidly identifying and thermodynamically ranking polymorphs. The new method employs high temperature and adiabatic decoupling to the simulation cell parameters in order to sample the Gibbs free energy of the polymorphs. Polymorphism in solid benzene is revisited, and a resolution to a long-standing controversy concerning the benzene II structure is proposed.