The dielectric function of a charged Bose gas is determined from the response to an imposed static sinusoidal electric field. Variational and diffusion quantum Monte Carlo simulations are used to calculate the ground-state properties of the system with trial wave functions containing a parameter dependent on the amplitude and wavelength of the perturbation. The induced charge is most efficiently extracted from the difference in ground-state energies at different magnitudes of the external field, rather than directly from the expectation value of the density fluctuation operator. Results are compared to the random-phase approximation for the weakly coupled fluid and to classical lattice values at low densities where the system forms a Wigner crystal. The dielectric function is also calculated at intermediate fluid densities and the transition from positive to negative response is found to occur in the metallic regime.The dielectric function of a charged Bose gas is determined from the response to an imposed static sinusoidal electric field. Variational and diffusion quantum Monte Carlo simulations are used to calculate the ground-state properties of the system with trial wave functions containing a parameter dependent on the amplitude and wavelength of the perturbation. The induced charge is most efficiently extracted from the difference in ground-state energies at different magnitudes of the external field, rather than directly from the expectation value of the density fluctuation operator. Results are compared to the random-phase approximation for the weakly coupled fluid and to classical lattice values at low densities where the system forms a Wigner crystal. The dielectric function is also calculated at intermediate fluid densities and the transition from positive to negative response is found to occur in the metallic regime.

Physical review. B, Condensed matterNov 15, 199238 citations

Quasicondensate and superfluid fraction in the two-dimensional charged boson gas at finite temperature

Ezio Strepparola, Anna Minguzzi, M. P. Tosi

The Bogoliubov--de Gennes equations are solved for the Coulomb Bose gas describing a fluid of charged bosons at finite temperature. The approach is applicable in the weak-coupling regime and the extent of its quantitative usefulness is tested in the three-dimensional fluid, for which diffusion Monte Carlo data are available on the condensate fraction at zero temperature. The one-body density matrix is then evaluated by the same approach for the two-dimensional fluid with ${e}^{2}/r$ interactions, to demonstrate the presence of a quasicondensate from its power-law decay with increasing distance and to evaluate the superfluid fraction as a function of temperature at weak coupling.The Bogoliubov--de Gennes equations are solved for the Coulomb Bose gas describing a fluid of charged bosons at finite temperature. The approach is applicable in the weak-coupling regime and the extent of its quantitative usefulness is tested in the three-dimensional fluid, for which diffusion Monte Carlo data are available on the condensate fraction at zero temperature. The one-body density matrix is then evaluated by the same approach for the two-dimensional fluid with ${e}^{2}/r$ interactions, to demonstrate the presence of a quasicondensate from its power-law decay with increasing distance and to evaluate the superfluid fraction as a function of temperature at weak coupling.

arXiv:cond-mat/0012171Physical review. B, Condensed matterFeb 14, 20018 citations

{e}^{2}/r

interactions, to demonstrate the presence of a quasicondensate from its power-law decay with increasing distance and to evaluate the superfluid fraction as a function of temperature at weak coupling.