title: Pfaffian pairing wave functions in electronic-structure quantum Monte Carlo simulations.
abstract: We investigate the accuracy of trial wave functions for quantum Monte Carlo based on Pfaffian functional form with singlet and triplet pairing. Using a set of first row atoms and molecules we find that these wave functions provide very consistent and systematic behavior in recovering the correlation energies on the level of 95%. In order to get beyond this limit we explore the possibilities of multi-Pfaffian pairing wave functions. We show that a small number of Pfaffians recovers another large fraction of the missing correlation energy comparable to the larger-scale configuration interaction wave functions. We also find that Pfaffians lead to substantial improvements in fermion nodes when compared to Hartree-Fock wave functions.
authors.affiliation: Center for High Performance Simulation and Department of Physics, North Carolina State University, Raleigh, North Carolina 27695, USA.
authors.forename: M
authors.initials: M
authors.lastname: Bajdich
authors.forename: L
authors.initials: L
authors.lastname: Mitas
authors.forename: G
authors.initials: G
authors.lastname: Drobný
authors.forename: L K
authors.initials: LK
authors.lastname: Wagner
authors.forename: K E
authors.initials: KE
authors.lastname: Schmidt