Non-orthogonal determinants in multi-Slater-Jastrow trial wave functions for fixed-node diffusion Monte Carlo

摘要: The accuracy and efficiency of ab-initio quantum Monte Carlo (QMC) algorithms benefits greatly from compact variational trial wave functions that accurately reproduce ground state properties a system. We investigate the possibility using multi-Slater-Jastrow with non-orthogonal determinants by optimizing identical single particle orbitals independently in separate determinants. As test case, we compute fixed-node diffusion (FN-DMC) energies C$_2$ molecule. For given multi-determinant expansion, find this orbital optimization results consistent improvement energy FN-DMC on order few tenths an eV. Our calculations indicate can improve computed QMC calculation when compared to their orthogonal counterparts.