Long wavelength behavior of the dynamical spin-resolved local-field factor in a two-dimensional electron liquid

The high frequency limits of the singular component $A(\omega)$ of the small wavevector expansion of the longitudinal (L) and transverse (T) components of the spin-resolved exchange-correlation kernel tensor $f_{xc,\sigma \sigma'}^{L,T}(q,\omega)=-v(q)G_{\sigma \sigma'}^{L,T}(q,\omega)$ in a two-dimensional isotropic electron liquid with arbitrary spin polarization are studied. Here $G_{\sigma \sigma'}^{L,T}(q,\omega)$ is the spin-resolved local field factor, $v(q)$ is the Coulomb interaction in momentum space, and $\sigma$ denotes spin. Particularly, the real part of $A(\omega)$ is found to be logarithmically divergent at large $\omega$. the large wavevetor structure of the corresponding spin-resolved static structure factor is also established

Static dielectric function with exact exchange contribution in the electron liquid

The exchange contribution, $\Pi_1 ({\bf k}, 0)$, to the static dielectric function in the electron liquid is evaluated exactly. Expression for it is derived analytically in terms of one quadrature. The expression, as presented in Eq. (3) in the Introduction, turns out to be very simple. A fully explicit expression (with no more integral in it) for $\Pi_1 ({\bf k}, 0)$ is further developed in terms of series. Equation (3) is proved to be equal to the expression obtained before under some mathematical assumption by Engel and Vosko, thus in the meanwhile putting the latter on a rigorous basis. The expansions of $\Pi_1 ({\bf k}, 0)$ at the wavectors of $k=0$, $k=2k_F$, and at limiting large $k$ are derived. The results all verify those obtained by Engel and Vosko.Comment: 15 page

On the performance of a hybrid genetic algorithm in dynamic environments

The ability to track the optimum of dynamic environments is important in many practical applications. In this paper, the capability of a hybrid genetic algorithm (HGA) to track the optimum in some dynamic environments is investigated for different functional dimensions, update frequencies, and displacement strengths in different types of dynamic environments. Experimental results are reported by using the HGA and some other existing evolutionary algorithms in the literature. The results show that the HGA has better capability to track the dynamic optimum than some other existing algorithms.Comment: This paper has been submitted to Applied Mathematics and Computation on May 22, 2012 Revised version has been submitted to Applied Mathematics and Computation on March 1, 201

Asymptotic near nucleus structure of the electron-interaction potential in local effective potential theories

In local effective potential theories of electronic structure, the electron correlations due to the Pauli exclusion principle, Coulomb repulsion, and correlation-kinetic effects, are all incorporated in the local electron-interaction potential $v_{ee}({\bf r})$. In previous work, it has been shown that for spherically symmetric or sphericalized systems, the asymptotic near nucleus expansion of this potential is $v_{ee}(r) = v_{ee}(0) + \beta r + O(r^2)$, with $v_{ee}(0)$ being finite. By assuming that the Schr\"odinger and local effective potential theory wave functions are analytic near the nucleus of atoms, we prove the following via Quantal density functional theory (Q-DFT): (i) correlations due to the Pauli principle and Coulomb correlations do not contribute to the linear structure; (ii) these Pauli and Coulomb correlations contribute quadratically; (iii) the linear structure is {\em solely} due to correlation-kinetic effects, the contributions of these effects being determined analytically. We also derive by application of adiabatic coupling constant perturbation theory via Q-DFT (iv) the asymptotic near nucleus expansion of the Hohenberg-Kohn-Sham theory exchange $v_x({\bf r})$ and correlation $v_c({\bf r})$ potentials. These functions also approach the nucleus linearly with the linear term of $v_x({\bf r})$ being {\em solely} due to the lowest-order correlation kinetic effects, and the linear term of $v_c({\bf r})$ being due {\em solely} to the higher-order correlation kinetic contributions. The above conclusions are equally valid for systems of arbitrary symmetry, provided spherical averages of the properties are employed.Comment: 9 pages. Accepted for publication in Phys. Rev.