Molecular simulation of solid–solid phase transitions

Abstract

Applications of dl_poly to solid–solid phase transitions are reviewed, with particular attention to how details of the mechanisms of the transitions may be extracted from molecular dynamics simulations. Two examples in molecular crystals are discussed: the order–disorder transition of p-terphenyl initiated at around 200 K by the unlocking of ring flipping; and the rotator phases of n-alkanes with around 20 carbon atoms per chain, showing distinct molecular mechanisms in the dynamics just below the melting points of odd and even chains. Covalent-ionic materials are represented by an application to an aluminophophate molecular sieve, AlPO₄-5.

Keywords:

• Phase transition
• dl_poly
• Alkane
• p-Terphenyl
• Aluminophosphate

Acknowledgements

Part of the simulations were performed on the parallel computers of the M3PEC regional consortium for high performance computing, Université de Bordeaux I.