Variational density matrix approach to the temperature-dependent elementary excitation spectrum of two-dimensional liquid4He |
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Authors: | Chung-In Um Jae-Rok Kahng Kyu-Hwang Yeon Thomas F. George |
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Affiliation: | (1) Department of Physics, College of Science, Korea University, 136-701 Seoul, Korea;(2) Department of Physics, Chungbuk National University, 306-763 Cheong Ju, Chung Buk, Korea;(3) Departments of Chemistry and Physics, Washington State University, 99164-1046 Pullman, Washington, USA |
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Abstract: | Using the variational density matrix method, we obtain a temperature-dependent elementary excitation spectrum for two-dimensional liquid4He. For more precise results, we use a Jastrow-Feenberg-type trial wave function and include the contribution of elementary diagrams within the hypernetted chain approximation. The behavior of the excitation spectrum as a function of the temperature and density in two dimensions is similar to that of the bulk system, but has a smaller roton minimum. The roton minimum of the excitation spectrum decreases with increasing temperature and increases with increasing density at low densities but decreases at large densities. The results agree well with Monte Carlo calculations and are closer than pevious theories to experimental measurements of4He film adsorbed on substrates. |
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