Award Date

1-1-2000

Degree Type

Dissertation

Degree Name

Doctor of Philosophy (PhD)

Department

Physics

First Committee Member

Tao Pang

Number of Pages

84

Abstract

With developments in X-ray diffractometry, experimentalists have been able to resolve the complex structures that had eluded them in the past. One area of this interest is in the regime of alkali metals under pressure. For years, the alkali metals have been viewed as simple systems whose properties can be understood with fairly simple ideas. Under pressure, things get interesting and one observes complex crystal structures in all of the alkali metals under high enough pressure. What is more interesting is that there appears to be many similarities in the phase diagrams of the alkali metals. This hints that this complexity is related to the similarities in the electronic structure of the different alkali metals. Fundamentally, one would like to know more about the electronic structure and its relation to the complex structures observed. This involves solving the Schroedinger equation for the particular system. Unfortunately, this equation is very difficult to solve exactly for more than two particles and the systems of interest are macroscopic containing on the order of 1020 electrons and nuclei; Since the development of quantum mechanics in 1918, much research has been done on simplifying the many-body Schroedinger equation. In many cases, the simplification of the Schroedinger equation involves making approximations that may or may not be applicable to every system. For the systems of high and nearly uniform density, one of the best approximations is Density-Functional theory. This theory has been used successfully in many calculations of the properties of various systems. Unfortunately, it has also been known to fail as well; It is my goal in this dissertation to use the density functional method to study solid rubidium at different and extremely high pressures on the order of 105 atmospheres. In Chapter 1, the complicated structures of the alkali metals K, Rb, and Cs at high pressure will be discussed. The density functional method and some of the related theories preceding it will be summarized in Chapter 2. Next, in Chapter 3, the pseudopotential approximation, which will be used in conjunction with the density functional method, is described. In Chapter 4, some of the details and theory about implementing both density functional theory and the pseudopotential approximation are highlighted. Finally, in Chapters 5 and 6, the details of the calculations will be discussed. The final conclusions and discussion will be given in Chapter 7.

Keywords

Alkali Metals; Calculation; Density; Density Functional Theory; Functional; Pressure; Pseudopotential; Rubidium; Under

Controlled Subject

Condensed matter; Physics

File Format

pdf

File Size

1853.44 KB

Degree Grantor

University of Nevada, Las Vegas

Language

English

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