A seven-site atom-atom potential model has been developed to describe the interactions between tetraphosphorus triselenide (P 4 Se 3 ) molecules. When used in molecular dynamics calculations the model predicts a transition to an orientationally disordered phase at a temperature close to that of the experimentally observed disordering transition. The predicted melting temperature of the model also is in good agreement with experiment. Below the transition, reorientation of the P 4 Se 3 molecules is of purely librational character. Above the transition, the molecules rotate about all three principal axes, but end-over-end rotation of the molecule is favoured relative to spinning motion around the threefold axis; the rotation becomes more isotropic as the temperature increases. Orientational disordering is shown to be accompanied by a transition to a hexagonal-close-packed structure. The positions and intensities of lines in the X-ray scattering pattern of the model system suggest that the structure of the disordered phase is the same as that of a previously uncharacterized plastic-crystalline modification already studied experimentally by Blachnik and Wickel. The work points to the need for further X-ray or neutron scattering studies of the high-temperature solid phases

Molecular dynamics study of the plastic-crystalline phase transition of tetraphosphorus triselenide / Alessandro, Sergi; Ferrario, Mauro; Stephen, Elliott; Ian, Mcdonald. - In: MOLECULAR PHYSICS. - ISSN 0026-8976. - STAMPA. - 84:(1995), pp. 727-742. [10.1080/00268979500100501]

Molecular dynamics study of the plastic-crystalline phase transition of tetraphosphorus triselenide

FERRARIO, Mauro;
1995-01-01

Abstract

A seven-site atom-atom potential model has been developed to describe the interactions between tetraphosphorus triselenide (P 4 Se 3 ) molecules. When used in molecular dynamics calculations the model predicts a transition to an orientationally disordered phase at a temperature close to that of the experimentally observed disordering transition. The predicted melting temperature of the model also is in good agreement with experiment. Below the transition, reorientation of the P 4 Se 3 molecules is of purely librational character. Above the transition, the molecules rotate about all three principal axes, but end-over-end rotation of the molecule is favoured relative to spinning motion around the threefold axis; the rotation becomes more isotropic as the temperature increases. Orientational disordering is shown to be accompanied by a transition to a hexagonal-close-packed structure. The positions and intensities of lines in the X-ray scattering pattern of the model system suggest that the structure of the disordered phase is the same as that of a previously uncharacterized plastic-crystalline modification already studied experimentally by Blachnik and Wickel. The work points to the need for further X-ray or neutron scattering studies of the high-temperature solid phases
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Molecular dynamics study of the plastic-crystalline phase transition of tetraphosphorus triselenide / Alessandro, Sergi; Ferrario, Mauro; Stephen, Elliott; Ian, Mcdonald. - In: MOLECULAR PHYSICS. - ISSN 0026-8976. - STAMPA. - 84:(1995), pp. 727-742. [10.1080/00268979500100501]
Alessandro, Sergi; Ferrario, Mauro; Stephen, Elliott; Ian, Mcdonald
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Utilizza questo identificativo per citare o creare un link a questo documento: https://hdl.handle.net/11380/741387
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