HR: 08:45h
AN: V21A-04 INVITED     [PDF]
TI: Quantum Monte Carlo Method for Materials --- Random Walks in Slater Determinant Space
AU: * Zhang, S
EM: shiwei@physics.wm.edu
AF: Department of Physics, College of William and Mary, Williamsburg, VA 23187 United States
AU: Krakauer, H
EM: krakauer@physics.wm.edu
AF: Department of Physics, College of William and Mary, Williamsburg, VA 23187 United States
AB: In order to reliably predict materials properties, it is critical to have accurate and robust calculations at the most fundamental level. Often the desired effects of the materials originate from electron interaction and correlation effects, and small errors in treating such effects will result in crucial and qualitative differences in the properties. Density functional approaches, despite its tremendous success in allowing detailed microscopic calculations of a variety of materials, is not always reliable. We have developed a new quantum Monte Carlo (QMC) method [1] for treating electron correlations. Similar to existing QMC methods, it allows calculations of ground-state equilibrium properties in CPU times that scale as a power law with system size. In addition it allows direct incorporation of state-of-the-art techniques (non-local pseudopotentials; high quality basis sets) from the very best mean-field calculations into a true many-body framework. The method projects out the many-body ground state by random walks in the space of Slater determinants. An approximate approach is formulated to control the phase problem with a trial wave function. The method allows the use of any one-particle basis. Using a plane-wave basis and non-local pseudopotentials, we apply the method to Be, Si, P atoms and dimers, and to bulk Si with 2, 16, 54 atom (216 electrons) supercells. Single Slater determinant wave functions from density functional theory calculations were used as the trial wave function with no additional optimization. The calculated dissociation energy of the dimer molecules and the cohesive energy of bulk Si are in excellent agreement with experiment and are comparable to or better than the best existing theoretical results. \\ {[1]} Shiwei Zhang and Henry Krakauer, Phys. Rev. Lett., 90, 136401 (2003).
DE: 2194 Instruments and techniques
SC: Volcanology, Geochemistry, Petrology [V]
MN: 2003 Fall Meeting