We propose improved versions of the standard diffusion Monte Carlo (DMC) and the lattice regularized diffusion Monte Carlo (LRDMC) algorithms. For the DMC method, we refine a scheme recently devised to treat nonlocal pseudopotential in a variational way. We show that such scheme-when applied to large enough systems-maintains its effectiveness only at correspondingly small enough time-steps, and we present two simple upgrades of the method which guarantee the variational property in a size-consistent manner. For the LRDMC method, which is size-consistent and variational by construction, we enhance the computational efficiency by introducing: (i) an improved definition of the effective lattice Hamiltonian which remains size-consistent and entails a small lattice-space error with a known leading term and (ii) a new randomization method for the positions of the lattice knots which requires a single lattice-space.
|Titolo:||Size-consistent variational approaches to nonlocal pseudopotentials: Standard and lattice regularized diffusion Monte Carlo methods revisited|
|Autori:||Casula, M; Moroni, S; Sorella, Sandro; Filippi, C.|
|Data di pubblicazione:||2010|
|Numero di Articolo:||154113|
|Digital Object Identifier (DOI):||10.1063/1.3380831|
|Appare nelle tipologie:||1.1 Journal article|