14 research outputs found
A unified approach to the density-potential mapping in a family of time-dependent density functional theories
It is shown that the density-potential mapping and the -representability problems in the time-dependent current density functional
theory (TDCDFT) are reduced to the solution of a certain many-body nonlinear
Schr\"odinger equation (NLSE). The derived NLSE for TDCDFT adds a link which
bridges the earlier NLSE-based formulations of the time-dependent deformation
functional theory (TDDefFT) and the time-dependent density functional theory
(TDDFT). We establish close relations between the nonlinear many-body problems
which control the existence of TDCDFT, TDDFT, and TDDefFT, and thus develop a
unified point of view on the whole family of the TDDFT-like theories.Comment: RevTeX4, 15 page
Spin dephasing in pseudomagnetic fields: susceptibility and geometry
We present a theory of spin dynamics caused by spin-orbit coupling for two-dimensional gases of cold atoms and other quasiparticles with pseudospin 1/2 moving in orbital gauge fields. Our approach is based on the gauge transformation in the form of a SU(2) rotation gauging out the spin-orbit coupling. As a result, the analysis of the spin dynamics is reduced to calculation of the density-related susceptibility of the system without spin-orbit coupling at the wavevector determined by the spin-rotation length. This approach allows one to treat the spin dynamics in terms of the linear response theory for bosonic and fermionic ensembles. We study different regimes of irreversible spin relaxation and coherent spin dynamics in these systems. For bosonic gases the effects of low temperature are crucial due to accumulation of particles in the small-momentum subspace even if the Bose–Einstein condensation does not occur due to the system low dimensionality
Local exchange-correlation vector potential with memory in Time-Dependent Density Functional Theory: the generalized hydrodynamics approach
Using Landau Fermi liquid theory we derive a nonlinear non-adiabatic
approximation for the exchange-correlation (xc) vector potential defined by the
xc stress tensor. The stress tensor is a local nonlinear functional of two
basic variables - the displacement vector and the second-rank tensor which
describes the evolution of momentum in a local frame moving with Eulerian
velocity. For irrotational motion and equilibrium initial state the dependence
on the tensor variable reduces to that on a metrics generated by a dynamical
deformation of the system.Comment: RevTex, 5 pages, no figures. Final version published in PR
Asymptotically exact dispersion relations for collective modes in a confined charged Fermi liquid
Using general local conservations laws we derive dispersion relations for
edge modes in a slab of electron liquid confined by a symmetric potential. The
dispersion relations are exact up to , where is a wave
vector and is an effective screening length. For a harmonic external
potential the dispersion relations are expressed in terms of the {\em exact}
static pressure and dynamic shear modulus of a homogeneous liquid with the
density taken at the slab core. We also derive a simple expression for the
frequency shift of the dipole (Kohn) modes in nearly parabolic quantum dots in
a magnetic field.Comment: RevTeX4, 4 pages. Revised version with new results on quantum qots
and wires. Published in Phys.Rev.
Collisionless hydrodynamics for 1D motion of inhomogeneous degenerate electron gases: equivalence of two recent descriptions
Recently I. Tokatly and O. Pankratov (''TP'', Phys. Rev. B 60, 15550 (1999))
used velocity moments of a semiclassical kinetic equation to derive a
hydrodynamic description of electron motion in a degenerate electron gas.
Independently, the present authors (Theochem 501-502, 327 (2000)) used
considerations arising from the Harmonic Potential Theorem (Phys. Rev. Lett.
73, 2244 (1994)) to generate a new form of high-frequency hydrodynamics for
inhomogeneous degenerate electron gases (HPT-N3 hydrodynamics). We show here
that TP hydrodynamics yields HPT-N3 hydrodynamics when linearized about a
Thomas-Fermi groundstate with one-dimensional spatial inhomnogeneity.Comment: 17p
Time-dependent density-functional and reduced density-matrix methods for few electrons: Exact versus adiabatic approximations
To address the impact of electron correlations in the linear and non-linear
response regimes of interacting many-electron systems exposed to time-dependent
external fields, we study one-dimensional (1D) systems where the interacting
problem is solved exactly by exploiting the mapping of the 1D -electron
problem onto an -dimensional single electron problem. We analyze the
performance of the recently derived 1D local density approximation as well as
the exact-exchange orbital functional for those systems. We show that the
interaction with an external resonant laser field shows Rabi oscillations which
are detuned due to the lack of memory in adiabatic approximations. To
investigate situations where static correlations play a role, we consider the
time-evolution of the natural occupation numbers associated to the reduced
one-body density matrix. Those studies shed light on the non-locality and
time-dependence of the exchange and correlation functionals in time-dependent
density and density-matrix functional theories.Comment: 19 pages, 13 figures, version as published apart from layou
Effective action and density functional theory
The effective action for the charge density and the photon field is proposed
as a generalization of the density functional. A simple definition is given for
the density functional, as the functional Legendre transform of the generator
functional of connected Green functions for the density and the photon field,
offering systematic approximation schemes. The leading order of the
perturbation expansion reproduces the Hartree-Fock equation. A renormalization
group motivated method is introduced to turn on the Coulomb interaction
gradually and to find corrections to the Hartree-Fock and the Kohn-Sham
schemes.Comment: New references and a numerical algorithm added, to appear in Phys.
Rev. B. 30 pages, no figure