6,128 research outputs found
Transport through a vibrating quantum dot: Polaronic effects
We present a Green's function based treatment of the effects of
electron-phonon coupling on transport through a molecular quantum dot in the
quantum limit. Thereby we combine an incomplete variational Lang-Firsov
approach with a perturbative calculation of the electron-phonon self energy in
the framework of generalised Matsubara Green functions and a Landauer-type
transport description. Calculating the ground-state energy, the dot
single-particle spectral function and the linear conductance at finite carrier
density, we study the low-temperature transport properties of the vibrating
quantum dot sandwiched between metallic leads in the whole electron-phonon
coupling strength regime. We discuss corrections to the concept of an
anti-adiabatic dot polaron and show how a deformable quantum dot can act as a
molecular switch.Comment: 10 pages, 8 figures, Proceedings of "Progress in Nonequilibrium
Green's Function IV" Conference, Glasgow 200
Leading-order behavior of the correlation energy in the uniform electron gas
We show that, in the high-density limit, restricted M{\o}ller-Plesset (RMP)
perturbation theory yields for the correlation energy per electron in the uniform electron gas,
where is the Seitz radius. This contradicts an earlier derivation which
yielded . The reason for the
discrepancy is explained.Comment: 4 pages, accepted for publication in Int. J. Quantum Che
Exact energy of the spin-polarized two-dimensional electron gas at high density
We derive the exact expansion, to , of the energy of the high-density
spin-polarized two-dimensional uniform electron gas, where is the Seitz
radius.Comment: 7 pages, 1 figure and 1 table, submitted to Phys. Rev.
The uniform electron gas
The uniform electron gas or UEG (also known as jellium) is one of the most
fundamental models in condensed-matter physics and the cornerstone of the most
popular approximation --- the local-density approximation --- within
density-functional theory. In this article, we provide a detailed review on the
energetics of the UEG at high, intermediate and low densities, and in one, two
and three dimensions. We also report the best quantum Monte Carlo and
symmetry-broken Hartree-Fock calculations available in the literature for the
UEG and discuss the phase diagrams of jellium.Comment: 37 pages, 8 figures, 8 tables, accepted for publication in WIRES
Computational Molecular Scienc
Correlation energy of two electrons in a ball
We study the ground-state correlation energy of two electrons of
opposite spin confined within a -dimensional ball () of radius .
In the high-density regime, we report accurate results for the exact and
restricted Hartree-Fock energy, using a Hylleraas-type expansion for the former
and a simple polynomial basis set for the latter. By investigating the exact
limiting correlation energy E_{\rm c}^{(0)} = \lim_{R \to 0} \Ec for various
values of , we test our recent conjecture [J. Chem. Phys. {\bf 131} (2009)
241101] that, in the large- limit, for
any spherically-symmetric confining external potential, where .Comment: 6 pages, 2 figure
Carrier-density effects in many-polaron systems
Many-polaron systems with finite charge-carrier density are often encountered
experimentally. However, until recently, no satisfactory theoretical
description of these systems was available even in the framework of simple
models such as the one-dimensional spinless Holstein model considered here. In
this work, previous results obtained using numerical as well as analytical
approaches are reviewed from a unified perspective, focussing on spectral
properties which reveal the nature of the quasiparticles in the system. In the
adiabatic regime and for intermediate electron-phonon coupling, a
carrier-density driven crossover from a polaronic to a rather metallic system
takes place. Further insight into the effects due to changes in density is
gained by calculating the phonon spectral function, and the fermion-fermion and
fermion-lattice correlation functions. Finally, we provide strong evidence
against the possibility of phase separation.Comment: 13 pages, 6 figures, accepted for publication in J. Phys.: Condens.
Matter; final versio
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