Electronic Structure of Condensed Matter

University Of Illinois At Urbana-Champaign, Urbana IL

Investigators

Abstract

0104399 Ceperley The long range goal of this research program is to develop practical, efficient theoretical methods to accurately predict the properties of many-electron systems. The methods and computational algorithms so generated can be applied to important idealized systems, such as the homogeneous electron gas, as well as to realistic problems in condensed matter. The rapid development of these computational quantum methods will have a qualitative impact upon the course of many fields of science including physics, materials science, chemistry and even biology. The approach is a combination of quantum Monte Carlo (QMC) simulations and density functional theory (DFT). QMC can provide exact results for some many-body problems, the principle goal is to extend the range of problems for which the method can be applied. On the other hand, DFT is the only current method feasible for accurate large-scale simulations of real systems. The research concerns both the basic theory, as well as tests of approximate forms using QMC. Continued development of QMC methods, with emphasis upon more accurate wavefunctions and improved boundary conditions and upon developing new methods able to use much larger computational facilities will be undertaken. Applications of QMC methods to physical problems will include nanoscale quantum devices and two-dimensional electron systems in the presence of disorder, where there is much experimental and theoretical controversy concerning the possible metal-insulator transition. General theoretical methods for studying dielectric polarization and functionals in correlated systems will be developed. We will extend the lattice model calculations to continuum systems that can serve as the basis for improved universal density-polarization functionals. We will also continue work started recently using time-dependent DFT to predict excitation spectra of materials, nanostructures and quantum dots. The first system studied will be silicon clusters, where intense blue light emission has been recently discovered. A long range goal is to develop both many-body methods and imporved functionals that can go beyond DFT approximations for ground state energies and excitation spectra. %%% The long range goal of this research program is to develop practical, efficient theoretical methods to accurately predict the properties of many-electron systems. The methods and computational algorithms so generated can be applied to important idealized systems, such as the homogeneous electron gas, as well as to realistic problems in condensed matter. The rapid development of these computational quantum methods will have a qualitative impact upon the course of many fields of science including physics, materials science, chemistry and even biology. ***