Phys. Rev. Lett. paper accepted

Fractional Charge by Fixed-Node Diffusion Monte Carlo Method (APS)

Matej Ditte; Matúš Dubecký

Abstract

Fixed-node diffusion Monte Carlo (FNDMC) method is a stochastic quantum many-body approach that has a great potential in electronic structure theory. We examine how FNDMC total energy E(N) satisfies exact constraints, linearity and derivative discontinuity, versus fractional electron number N, if combined with mean-field trial wave functions that miss such features. H and Cl atoms with fractional charge reveal that FNDMC method is well able to restore the piecewise linearity of E(N). The method uses ensemble and projector ingredients to achieve the correct charge localization. A water-solvated Cl− complex illustrates superior performance of FNDMC method for charged noncovalent systems.