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dc.contributor.authorHeiser, Gernot A.en_US
dc.date.accessioned2009-07-09T18:39:07Z
dc.date.available2009-07-09T18:39:07Z
dc.date.issued1984-07-09T18:39:07Z
dc.identifier.urihttp://hdl.handle.net/10464/1966
dc.description.abstractMolec ul ar dynamics calculations of the mean sq ua re displacement have been carried out for the alkali metals Na, K and Cs and for an fcc nearest neighbour Lennard-Jones model applicable to rare gas solids. The computations for the alkalis were done for several temperatures for temperature vol ume a swell as for the the ze r 0 pressure ze ro zero pressure volume corresponding to each temperature. In the fcc case, results were obtained for a wide range of both the temperature and density. Lattice dynamics calculations of the harmonic and the lowe s t order anharmonic (cubic and quartic) contributions to the mean square displacement were performed for the same potential models as in the molecular dynamics calculations. The Brillouin zone sums arising in the harmonic and the quartic terms were computed for very large numbers of points in q-space, and were extrapolated to obtain results ful converged with respect to the number of points in the Brillouin zone.An excellent agreement between the lattice dynamics results was observed molecular dynamics and in the case of all the alkali metals, e~ept for the zero pressure case of CSt where the difference is about 15 % near the melting temperature. It was concluded that for the alkalis, the lowest order perturbation theory works well even at temperat ures close to the melting temperat ure. For the fcc nearest neighbour model it was found that the number of particles (256) used for the molecular dynamics calculations, produces a result which is somewhere between 10 and 20 % smaller than the value converged with respect to the number of particles. However, the general temperature dependence of the mean square displacement is the same in molecular dynamics and lattice dynamics for all temperatures at the highest densities examined, while at higher volumes and high temperatures the results diverge. This indicates the importance of the higher order (eg. ~* ) perturbation theory contributions in these cases.en_US
dc.language.isoengen_US
dc.publisherBrock Universityen_US
dc.subjectMolecular dynamics.en_US
dc.subjectLeast squares.en_US
dc.subjectAlkali metals.en_US
dc.subjectRare gas compounds.en_US
dc.subjectLattice dynamics.en_US
dc.titleMolecular dynamics calculation of mean square displacement in alkali metals and rare gas solids and comparison with lattice dynamicsen_US
dc.typeElectronic Thesis or Dissertationen
dc.degree.nameM.Sc. Physicsen_US
dc.degree.levelMastersen_US
dc.contributor.departmentDepartment of Physicsen_US
dc.degree.disciplineFaculty of Mathematics and Scienceen_US
refterms.dateFOA2021-08-07T02:09:29Z


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