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LATTICE DYNAMICS OF MAGNESIUM OXIDE AND SIMULATION OF NORMAL - RUBIDIUM TETRACHLOROZINCATE
Abstract
The first of two subjects is a simple method for including the major effects of the crystal environment in a calculation of the distribution of electrons about an ion in the crystal without explicitly considering the electrons of the other ions. The method follows from first principles and is applicable to any crystal structure. The calculation of the single ion density is computationally simple, so the method is well suited for investigation of the properties of any crystal in which the effects of variations in the environments of individual ions are significant. As a sample application, the method is used to determine electron densities of the Mg('2+) and O('2-) ions in MgO. Pair potentials are obtained from the densities and are used to calculate some thermodynamical and optical properties of the crystal. The second subject is a computer simulation of the dynamics of the ions in the normal (high temperature) phase of rubidium tetrachlorozincate (Rb(,2)ZnCl(,4)). The purpose of the simulation is to understand the disordered structure of the normal phase and to investigate the possibility that the transition from that phase to another upon cooling is associated with the change from a disordered structure to an ordered one. We find a completely new structure that appears to have all of the characteristics of the real solid. The newly discovered structure is distinct from but so similar to the previously suggested structure of the solid that it could easily have been missed in the analysis of experimental data, particularly if the new structure had not been recognized as a possibility. Even if the new structure is not found in rubidium tetrachlorozincate, it offers a challenge to crystallographers to find it in some other material. We suggest that the onset correlation in the simulated disordered structure is the mechanism for the transition to the lower temperature phase.
Subject Area
Condensation
Recommended Citation
EDWARDSON, PAUL JOSEPH, "LATTICE DYNAMICS OF MAGNESIUM OXIDE AND SIMULATION OF NORMAL - RUBIDIUM TETRACHLOROZINCATE" (1986). ETD collection for University of Nebraska-Lincoln. AAI8624587.
https://digitalcommons.unl.edu/dissertations/AAI8624587