Excitations in liquid helium-4 films /
We use the hypernetted chain (HNC) variational theory for
| Main Author: | |
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| Format: | Thesis Book |
| Language: | English |
| Published: |
[Place of publication not identified] :
[publisher not identified] ;
1995.
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| Subjects: | |
| Online Access: | http://proxy.library.tamu.edu/login?url=http://proquest.umi.com/pqdweb?did=742145671&sid=1&Fmt=2&clientId=2945&RQT=309&VName=PQD |
| Summary: | We use the hypernetted chain (HNC) variational theory for inhomogeneous systems to study the excitations in 4 He films adsorbed to a graphite substrate. The first part of this dissertation describes the HNC variational theory and how it is used to calculate the physical properties of 4 He films. We then extend the theory to describe excitations in these films. The simplest implementation of the theory, which assumes time-dependent one-body correlations only, is the generalization of Feynman's theory of excitations to inhomogeneous geometries. We then include time-dependent fluctuations of the two-body correlations. This leads to two important improvements of the theory. First, the predictions of the new theory agree significantly better with experiments. Second, since the new theory also allows for damping effects, we can calculate the lifetimes of individual excitations. Insight can be gained into the physical nature of the film's excited states by studying the transition densities and the probability currents. We describe how these quantities can be calculated within the generalized theory of excitations, and present results for mono-, double- , and triple-layer films. |
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| Item Description: | Vita. "Major Subject: Physics". |
| Physical Description: | ix, 119 leaves : illustrations ; 28 cm. Issued also on microfiche from University Microfilms Inc. |
| Bibliography: | Includes bibliographical references. |