Showing papers by "Roberto Car published in 1987"
TL;DR: Calculated du spectre d'excitation optique and du coefficient de diffusion des electrons; bon accord avec les valeurs experimentales.
Abstract: The electronic states and dynamical properties of dilute liquid K-KCl solutions are studied by simultaneous integration of the coupled time-dependent Schr\"odinger equation for the excess electrons and classical equations of motion for the ions. Excess electrons are found to spend most of their time in localized F-center states, whose size and shape can fluctuate significantly. Transport is mostly due to jumps between localized states, with a jumping rate \ensuremath{\simeq}3\ifmmode\times\else\texttimes\fi{}${10}^{12}$ ${\mathrm{s}}^{\mathrm{\ensuremath{-}}1}$. The optical excitation spectrum and the electron diffusion coefficient are calculated and found to be in agreement with the experimental data.
143 citations
TL;DR: The equilibrium geometries of selenium clusters Se 3 to Se 8 have been calculated using a parameter-free density functional method, and the most prominent low-energy structures are found using combined molecular dynamics and simulated annealing techniques as mentioned in this paper.
139 citations
TL;DR: In this paper, the authors used spin density functional theory to describe the interaction between solvated electrons in KCl in the high dilution limit and found that electrons repel each other and localize into separate F-center-like states.
Abstract: Spin density functional theory is used to describe the interaction between solvated electrons in KCl in the high dilution limit. In agreement with recent calculations based on the path integral method our results for antiparallel spin predict a strong tendency to form localized bielectronic complexes. At variance with numerical path integral, our method can efficiently treat the case of parallel spins. For this case we find that electrons repel each other and localize into separate F-center-like states.
36 citations
TL;DR: In this paper, the Lagrangean is modified with the introduction of an auxiliary field that represents the Hartree potential, leading to the same results as the present version of the theory.
33 citations
01 Jan 1987
TL;DR: In this paper, the relevance of the Unified Molecular Dynamics (Density Functional) approach to the study of cluster physics is discussed, and specific calculations for small Si aggregates are presented, and ground-state structures can be efficiently obtained with a dynamical simulated annealing.
Abstract: We discuss the relevance of the Unified Molecular Dynamics — Density Functional approach to the study of cluster physics. We present specific calculations for small Si aggregates, and show that ground-state structures can be efficiently obtained with a dynamical simulated annealing. We find that, while the T=0 equilibrium structures are symmetrical, the atomic configurations which correspond to the local minima close in energy to the ground state are disordered. These appear to be the relevant structures at high temperatures.
9 citations