8:00 AM–10:36 AM, Thursday, March 16, 2006
Baltimore Convention Center - 324
Sponsoring Unit:
DCMP
Chair: Andrew Williamsom, Lawrence Livermore National Laboratory
Abstract ID: BAPS.2006.MAR.U27.5
8:48 AM–9:00 AM
Wirawan Purwanto
Malliga Suewattana
Henry Krakauer
Shiwei Zhang
Eric J. Walter
(College of William and Mary, VA)
We study the ground-state properties of second-row atoms and molecules using the phaseless auxiliary-field quantum Monte Carlo (AF QMC) method.\footnote{S. Zhang and H. Krakauer, Phys. Rev. Lett. \textbf{90}, 136401 (2003)} This method projects the many-body ground state from a trial wave function by means of random walks in the Slater-determinant space. We use a single Slater-determinant trial wave function obtained from density-functional theory (DFT) or Hartree-Fock (HF) calculations. The calculations were done with a plane-wave basis and supercells with periodic boundary condition. We investigate the finite-size effects and the accuracy of pseudopotentials within DFT, HF, and AF QMC frameworks. Pseudopotentials generated from both LDA (OPIUM\footnote{\texttt{http://opium.sourceforge.net}}) and HF\footnote{I. Ovcharenko, A. Aspuru-Guzik, and W. A. Lester, J. Chem. Phys. \textbf{114}, 7790 (2001)} are employed. We find that the many-body QMC calculations show a greater sensitivity to the accuracy of the pseudopotentials. With reliable pseudopotentials, the ionization potentials and dissociation energies obtained using AF QMC are in excellent agreement with the experimental results.
To cite this abstract, use the following reference: http://meetings.aps.org/link/BAPS.2006.MAR.U27.5