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

Trie 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 kno~vn diffraction data. Correlation densities of orientational and translational variables are computed showing orientation-translation coupling of trie perchlorate ions, and coupling between a perchlorate orientation and trie translation of neighbouring potassium and perchlorate ions. Trie orientation-orientation coi-relation between neighbouring perchlorate ions shows antiferromagnetic pseudo-spin type coupling corresponding to ions in opposite Td orientations. This correlation bas a lifetime which is longer than trie single molecule orientational lifetime, evidence of correlated orientational motion. PACS. 61.12-q Neutron diffraction and scattering. PACS. 61.43-j Disordered solids. PACS. 61.43Bn Structural modehng: serial-addition models, computer simulation.