Orientational order-disorder transition on a surface

A system of diatomic molecules with atoms interacting via Lennard-Jones potential and with the centers of mass of molecules fixed on a square lattice is studied by molecular dynamics technique. Temperature dependences of internal energy and orientational order parameter are calculated. The development of an ordered state from a disordered state is also studied. It is found that the system undergoes a continuous orientational order-disorder transition. © 1982 The American Physical Society.