2000 character limit reached
Beyond the Born-Oppenheimer approximation with quantum Monte Carlo (1407.3788v1)
Published 14 Jul 2014 in physics.chem-ph, cond-mat.str-el, and quant-ph
Abstract: In this work we develop tools that enable the study of non-adiabatic effects with variational and diffusion Monte Carlo methods. We introduce a highly accurate wave function ansatz for electron-ion systems that can involve a combination of both fixed and quantum ions. We explicitly calculate the ground state energies of H${2}$, LiH, H${2}$O and FHF${-}$ using fixed-node quantum Monte Carlo with wave function nodes that explicitly depend on the ion positions. The obtained energies implicitly include the effects arising from quantum nuclei and electron-nucleus coupling. We compare our results to the best theoretical and experimental results available and find excellent agreement.