Roi Baer
Department of Physical Chemistry and the Lise Meitner Minerva-Center for Computational Quantum Chemistry, The Hebrew University of Jerusalem, Jerusalem 91904 Israel.

Daniel Neuhauser
Department of Chemistry and Biochemistry, University of California, Los Angeles CA 90095, USA.

Shifted contour auxiliary field Monte Carlo is implemented for molecular electronic structure using a plane waves basis and norm conserving pseudopotentials. A methodology is developed to overcome the slow convergence of the total electronic energy with simulation cell size. The method is used to compute H₂, BeH₂ and Be₂ atomization energies. By comparing with high correlation methods, DFT-based norm conserving pseudopotentials are evaluated for performance in fully correlated molecular computations. Pseudopotentials based on generalized gradient approximation lead to consistently better atomization energies than those based on the local density approximation. The accuracy achieved is limited by the pseudopotentials to around 0.1 eV.