MOLECULAR-DYNAMICS SIMULATION OF FERROELECTRIC CLUSTERS

Stoichiometric clusters with zero dipole moment are constructed from the perovskite structure by cleaving along the 8 111 and 6 100 planes positioned equal distances from an origin midway between the two cations. The procedure is used to form clusters of NaCaF3, a hypothetical material which is predicted to be ferroelectric in the rigid-ion approximation. Results of molecular-dynamics calculations are reported for several clusters ranging in size from N=35 to 5900 ions. Calculations for the larger clusters were carried out on a massively parallel computer. A clear ferroelectric transition is observed for clusters with N800. © 1995 The American Physical Society.