Physical Review B 78, 195310 (2008)

Diffusion Monte Carlo study of a valley degenerate electron gas and application to quantum dots

G. J. Conduit1 and P. D. Haynes2

1Theory of Condensed Matter, Department of Physics, University of Cambridge, Cavendish Laboratory, 19 J. J. Thomson Avenue, Cambridge CB3 0HE, UK
2Departments of Physics and Materials, Imperial College London, Exhibition Road, London SW7 2AZ, UK

A many-flavor electron gas (MFEG) in a semiconductor with a valley degeneracy ranging between 6 and 24 was analyzed using diffusion Monte Carlo (DMC) calculations. The DMC results compare well with an analytic expression derived by one of us [Phys. Rev. B 78, 035111 (2008)] for the total energy to within ±1 % over an order of magnitude range of density, which increases with valley degeneracy. For Bi2Te3 (six-fold valley degeneracy) the applicable charge carrier densities are between 7×1019 cm-3 and 2×1020 cm-3. DMC calculations distinguished between an exact and a useful approximate expression for the 24-fold degenerate MFEG polarizability for wave numbers 2pF < q < 7pF. The analytical result for the MFEG is generalized to inhomogeneous systems by means of a gradient correction, the validity range of this approach is obtained. Employed within a density-functional theory calculation this approximation compares well with DMC results for a quantum dot.

Last updated: 5 August 2010