PROJECTS

Development of electron structure quantum Monte Carlo methods

PRINCIPAL INVESTIGATOR

PROJECT RESEARCH ASSISTANT

ABSTRACT

The full electronic many-body problem for molecules can be solved numerically with the quantum Monte Carlo (DQMC) method. The method is based on the transformation of the time dependent Schrödinger equation into a diffusion equation and on the direct simulation of the diffusion process with the computer. Therefore, the electron correlation is calculated directly. Because of the direct quantum simulation, the DQMC method is very accurate but also time consuming and provides an approach conceptually very different from orbital-based ab initio methods. The electronic energy is obtained as weighted average of the local energy EL= q-1Hq over a diffusion trajectory where q is an approximation to the exact wave function. The usual calculation of the local energy scales like n3 with the number of electrons n. A goal of this proposal is the development of linear scaling methods for the local energy such that routinely highly accurate all-electron DQMC calculations for about 50 non-hydrogen atoms will be possible. In addition to improving the computational demand, the extension of the DQMC method to electronically excited states will be developed.