Mark Rasolt

Magnetic Fields and Density Functional Theory

Publisher Summary The current-density-functional theory ( CSDFT) reviewed in this chapter is a rigorous formulation of a many-body problem of nonrelativistic interacting fermions in gauge fields. In addition to spin polarization, it includes for the first time the effect of orbital currents. A central result is the self-consistent Schroedinger-type equation showing that the replacement of the external vector potential by an effective one (including exchange-correlation effects) must be done in the linear term but not in the quadratic one. Although, at first sight, this appears to violate gauge invariance and hence the continuity equation a careful consideration of the transformation of the effective potentials based on the symmetry of exchange-correlation energy reveals that there is no such violation. The emphasis is on the appearance of an exchange-correlation contribution to the vector potential has nothing to do with the fact circulating currents generate, according to Maxwells equations, a “classical” contribution to the magnetic field. This effect is extremely small and could be accounted for by replacing the external vector potential by the self-consistent potential.

Plasmon‐phonon‐assisted electron‐hole recombination in silicon at high laser fluence

We present both theoretical and experimental results in silicon which clearly demonstrate that at time scales of 20 to 40 ps, after the pump laser pulse and at fluences greater than 100 mJ/cm2, the carrier density of the electron‐hole plasma drops for increasing fluence; this is not explained by Auger recombination. We show that this drop is specific to plasmon‐phonon‐assisted recombination, which naturally explains this behavior.

Exchange splitting of ferromagnetic nickel within the local potential approximation

Abstract It is shown that the first higher-order correction to the local spin-polarized potential, as derived from electron gas considerations, does not resolve the discrepancy concerning the exchange splitting of ferromagnetic nickels band structure.

Realistic Anderson lattice model of the 214 material solved in mean field

Abstract A realistic Anderson Lattice model of the La high-T c material based on an optimal tight binding fit to the LAPW band structure and an Anderson U within the Cu d-orbitals is written in terms of slave bosons and solved in mean field approximation. The magnetic susceptibility, specific heat, thermopower and Hall coefficient and the behaviour of T c with doping are calculated, and successfully compared with the data.

Pair potentials at simple metal surfaces

Abstract Screened pair potentials at simple metal surfaces are treated within linear response theory. Quantum interference effects and terms that do not depend on the shape of the surface potential energy barrier are separated in a clear fashion.

Role of gradient corrections in interpolation formulae for surface energies

Abstract The contribution of lowest order exchange and correlation gradient corrections to metallic surface energy wavevector decompositions is calculated as a function of wavenumber. A wavevector interpolation scheme based on correcting the local density approximation by both surface plasmons and gradient corrections is proposed.

Small and large wave vector behavior for the structure factor of an interacting nonuniform electron gas

Abstract We show that the structure factir of an interacting nonuniform electron gas does not go to zero at small q , as one might conclude from the conservation of particles sum rule, and is not given rigorously in the local density approximation at large q .

Exchange contribution to the surface energy of an arbitrary fermion system within the infinite barrier model

Abstract The surface energy of a many electron system within the infinite barrier model has produced a considerable amount of interest. These studies have provided solutions for the exchange and correlation (within the RPA) surface energies with which approximate treatments of more realistic surfaces have been compared. In this note we present the first generalization, within this model, of the exchange contribution to the surface energy for a general Fermion system of arbitrary interparticle interaction. Such results should be useful for testing approximate methods for a much wider range of Fermion systems.

Energetics and lattice relaxation of light impurities in aluminum

We present results of calculations for a series of impurities He, Li, Be, B, C, N, O, F, and Ne in an Al lattice, using the spherical-solid model. The relaxation displacements of the ions around the impurities at the octahedral site (i) vary rather smoothly with the impurity atomic number and (ii) show some structure. These results cannot be correlated with the size of the impurity in its atomic state, but involve the details of the density displaced in the host.

The surface exchange energy of a metal for the full range of wave vector fluctuations

Abstract The exchange energy for a finite barrier model of realistic density profile variation is studied as a function of the full range of wave vector fluctuations. The deviation between the exact and approximate treatments is examined with particular attention to the small wave vector behavior.