228 research outputs found
Density-to-potential map in time-independent excited-state density-functional theory
In light of the recent work by Sahni et al., Harbola, and Gaudoin and Burke,
the question of mapping from an excited-state density of a many-electron
interacting system to the potential of the related non-interacting system is
analyzed. To do so, we investigate the Levy-Nagy criterion quantitatively for
several excited-states. Our work indicates that Levy-Nagy criterion may fix the
density to potential map uniquely
Kirzhnits gradient expansion for a D-dimensional Fermi gas
For an ideal D-dimensional Fermi gas under generic external confinement we
derive the correcting coefficient of the von Weizsacker term in the
kinetic energy density. To obtain this coefficient we use the Kirzhnits
semiclassical expansion of the number operator up to the second order in the
Planck constant . Within this simple and direct approach we determine
the differential equation of the density profile and the density functional of
the Fermi gas. In the case D=2 we find that the Kirzhnits gradient corrections
vanish to all order in .Comment: 6 pages, 0 figures, accepted for publication in J. Phys. A: Math.
Theo
Simple model of the static exchange-correlation kernel of a uniform electron gas with long-range electron-electron interaction
A simple approximate expression in real and reciprocal spaces is given for
the static exchange-correlation kernel of a uniform electron gas interacting
with the long-range part only of the Coulomb interaction. This expression
interpolates between the exact asymptotic behaviors of this kernel at small and
large wave vectors which in turn requires, among other thing, information from
the momentum distribution of the uniform electron gas with the same interaction
that have been calculated in the G0W0 approximation. This exchange-correlation
kernel as well as its complement analogue associated to the short-range part of
the Coulomb interaction are more local than the Coulombic exchange-correlation
kernel and constitute potential ingredients in approximations for recent
adiabatic connection fluctuation-dissipation and/or density functional theory
approaches of the electronic correlation problem based on a separate treatment
of long-range and short-range interaction effects.Comment: 14 pages, 14 figures, to be published in Phys. Rev.
Differential virial theorem in relation to a sum rule for the exchange-correlation force in density-functional theory
Holas and March [Phys. Rev. A.51, 2040 (1995)] gave a formally exact theory for the exchange-correlation (xc) forceF xc (r)=−∇υ xc (r) associated with the xc potentialυ xc (r) of the density-functional theory in terms of low-order density matrices. This is shown in the present study to lead, rather directly, to the determination of a sum rule [nFxc]=0 relating the xc force with the ground-state density nr. Some connection is also made with an earlier result relating to the external potential by Levy and Perdew [Phys. Rev. A.32, 2010 (1985)] and with the quite recent study of Joubert [J. Chem. Phys.119, 1916 (2003)] relating to the separation of the exchange and correlation contributions.A.R. was partially supported by the EC Sixth Framework Network of Excellence NANOQUANTA NMP4-CT-2004-500198, the Spanish MCyT, and the Humboldt Foundation under the Bessel research award 2005.Peer Reviewe
The influence of local field corrections on Thomson scattering in non-ideal two-component plasmas
Thomson scattering in non-ideal (collision-dominated) two-component plasmas
is calculated accounting for electron-ion collisions as well as
electron-electron correlations. This is achieved by using a novel interpolation
scheme for the electron-electron response function generalizing the traditional
Mermin approach. Also, ions are treated as randomly distributed inert
scattering centers. The collision frequency is taken as a dynamic and complex
quantity and is calculated from a microscopic quantum-statistical approach.
Implications due to different approximations for the electron-electron
correlation, i.e. different forms of the OCP local field correction, are
discussed
Anti-adiabatic limit of the exchange-correlation kernels of an inhomogeneous electron gas
We express the high-frequency (anti-adiabatic) limit of the
exchange-correlation kernels of an inhomogeneous electron gas in terms of the
following equilibrium properties: the ground-state density, the kinetic stress
tensor, the pair-correlation function, and the ground-state
exchange-correlation potential. Of these quantities, the first three are
amenable to exact evaluation by Quantum Monte Carlo methods, while the last can
be obtained from the inversion of the Kohn-Sham equation for the ground-state
orbitals. The exact scalar kernel, in this limit, is found to be of very long
range in space, at variance with the kernel that is used in the standard local
density approximation. The anti-adiabatic xc kernels should be useful in
calculations of excitation energies by time-dependent DFT in atoms, molecules,
and solids, and provides a solid basis for interpolation between the low- and
high-frequency limits of the xc kernels.Comment: 9 pages, 3 figures, to be submitted to PR
Structure of the Local-field factor of the 2-D electron fluid. Possible evidence for correlated scattering of electron pairs
The static local-field factor (LFF) of the 2-D electron fluid is calculated
{\it nonperturbatively} using a mapping to a classical Coulomb fluid
Phys. Rev. Lett., {\bf 87}, 206. The LFF for the paramagnetic
fluid {\it differs markedly} from perturbation theory where a maximum near
2 is expected. Our LFF has a quasi-linear small-k region leading to a
maximum close to 3, in agreent with currently available quantum Monte
Carlo data. The structure in the LFF and its dependence on the density and
temperature are interpretted as a signature of correlated scattering of
electron pairs of opposite spin.The lack of structure at implies
weakened Friedel oscillations, Kohn anomalies etc.Comment: 4 pages, 3 figures, version 2 of condmat/0304034, see
http://nrcphy1.phy.nrc.ca/ims/qp/chandre/chnc/ Changs in the text, figure 2
and updated reference
Hartree-Fock method posed as a density-functional theory: Application to the Be atom
The Hartree-Fock ground-state energy and electron density are first shown to be derivable from a local one-body effective potential v(r). As a nontrivial example, attention is then focused on the Be atom and isoelectronic atomic ions, the wave functions being written in terms of the density amplitude and phase. Some related general comments on the two-level one-dimensional system are included; kinetic-energy density is shown to be a local functional of electron density generated by the harmonic-oscillator potential
Scaling in the correlation energies of two-dimensional artificial atoms
We find an unexpected scaling in the correlation energy of artificial atoms,
i.e., harmonically confined two-dimensional quantum dots. The scaling relation
is found through extensive numerical examinations including Hartree-Fock,
variational quantum Monte Carlo, density-functional, and full
configuration-interaction calculations. We show that the correlation energy,
i.e., the true ground-state total energy subtracted by the Hartree-Fock total
energy, follows a simple function of the Coulomb energy, confimenent strength
and, the number of electrons. We find an analytic expression for this function,
as well as for the correlation energy per particle and for the ratio between
the correlation and total energies. Our tests for independent diffusion Monte
Carlo and coupled-cluster results for quantum dots -- including open-shell data
-- confirm the generality of the obtained scaling. As the scaling is also well
applicable to 100 electrons, our results give interesting prospects
for the development of correlation functionals within density-functional
theory.Comment: Accepted to Journal of Physics: Condensed Matte
Polarizational stopping power of heavy-ion diclusters in two-dimensional electron liquids
The in-plane polarizational stopping power of heavy-ion diclusters in a
two-dimensional strongly coupled electron liquid is studied. Analytical
expressions for the stopping power of both fast and slow projectiles are
derived. To go beyond the random-phase approximation we make use of the inverse
dielectric function obtained by means of the method of moments and some recent
analytical expressions for the static local-field correction factor.Comment: 9 pages, 5 figures. Published in Physical Review B
http://link.aps.org/abstract/PRB/v75/e11510
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