Dynamics of a Two-Dimensional System of Quantum Dipoles
- Departament de Fisica i Enginyeria Nuclear, Campus Nord B4-B5, Universitat Politecnica de Catalunya, E-08034 Barcelona (Spain)
- Institut fuer Theoretische Physik, Johannes-Kepler Universitaet, Altenbergerstr. 69, 4040 Linz (Austria)
A detailed microscopic analysis of the dynamic structure function S(k,{omega}) of a two-dimensional Bose system of dipoles polarized along the direction perpendicular to the plane is presented and discussed. Starting from ground-state quantities obtained using a quantum diffusion Monte Carlo algorithm, the density-density response is evaluated in the context of the correlated basis functions (CBF) theory. CBF predicts a sharp peak and a multiexcitation component at higher energies produced by the decay of excitations. We discuss the structure of the phonon-roton peak and show that the Feynman and Bogoliubov predictions depart from the CBF result already at low densities. We finally discuss the emergence of a roton in the spectrum, but find the roton energy not low enough to make the system unstable under density fluctuations up to the highest density considered that is close to the freezing point.
- OSTI ID:
- 21180291
- Journal Information:
- Physical Review Letters, Vol. 102, Issue 11; Other Information: DOI: 10.1103/PhysRevLett.102.110405; (c) 2009 The American Physical Society; Country of input: International Atomic Energy Agency (IAEA); ISSN 0031-9007
- Country of Publication:
- United States
- Language:
- English
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