A Molecular Dynamics Simulation of the Orientationaly Disordered Phase of Potassium Perchlorate

Abstract
The orientationaly disordered phase of a relatively large system of potassium perchlorate is simulated on a massively parallel computer with strict SIMD architecture. Crystallographic results are compared with known diffraction data. Correlation densities of orientational and translational variables are computed showing orientation-translation coupling of the perchlorate ions, and coupling between a perchlorate orientation and the translation of neighbouring potassium and perchlorate ions. The orientation-orientation correlation between neighbouring perchlorate ions shows antiferromagnetic pseudo-spin type coupling corresponding to ions in opposite orientations. This correlation has a lifetime which is longer than the single molecule orientational lifetime, evidence of correlated orientational motion.