title: Communication: stochastic evaluation of explicitly correlated second-order many-body perturbation energy.
abstract: A stochastic algorithm is proposed that can compute the basis-set-incompleteness correction to the second-order many-body perturbation (MP2) energy of a polyatomic molecule. It evaluates the sum of two-, three-, and four-electron integrals over an explicit function of electron-electron distances by a Monte Carlo (MC) integration at an operation cost per MC step increasing only quadratically with size. The method can reproduce the corrections to the MP2/cc-pVTZ energies of H2O, CH4, and C6H6 within a few mEh after several million MC steps. It circumvents the resolution-of-the-identity approximation to the nonfactorable three-electron integrals usually necessary in the conventional explicitly correlated (R12 or F12) methods.
authors: Department of Chemistry, University of Illinois at Urbana-Champaign, Urbana, Illinois 61801, USA.
authors: Soohaeng Yoo
authors: SY
authors: Willow
authors: Department of Chemistry, Virginia Tech, Blacksburg, Virginia 24061, USA.
authors: Jinmei
authors: J
authors: Zhang
authors: Department of Chemistry, Virginia Tech, Blacksburg, Virginia 24061, USA.
authors: Edward F
authors: EF
authors: Valeev
authors: Department of Chemistry, University of Illinois at Urbana-Champaign, Urbana, Illinois 61801, USA.
authors: So
authors: S
authors: Hirata