Exploration of Brueckner orbital trial wave functions in diffusion Monte Carlo calculations

â¿¢Brueckner orbitals are used as a trial wave function for diffusion Monte Carlo calculations.â¿¢For neutral systems, Brueckner orbitals result in a lower DMC energy than Hartreeâ¿¿Fock orbitals.â¿¢For a CO2 anion, DMC energies are lowest when a Brueckner trial wave function is used.