title: Including nuclear quantum effects into highly correlated electronic structure calculations of weakly bound systems.
abstract: An interface between the APMO code and the electronic structure package MOLPRO is presented. The any particle molecular orbital APMO code [González et al., Int. J. Quantum Chem. 108, 1742 (2008)] implements the model where electrons and light nuclei are treated simultaneously at Hartree-Fock or second-order Möller-Plesset levels of theory. The APMO-MOLPRO interface allows to include high-level electronic correlation as implemented in the MOLPRO package and to describe nuclear quantum effects at Hartree-Fock level of theory with the APMO code. Different model systems illustrate the implementation: (4)He2 dimer as a protype of a weakly bound van der Waals system; isotopomers of [He-H-He](+) molecule as an example of a hydrogen bonded system; and molecular hydrogen to compare with very accurate non-Born-Oppenheimer calculations. The possible improvements and future developments are outlined.
authors.affiliation: Instituto de Física Fundamental (C.S.I.C.), Serrano 123, E-28006 Madrid, Spain.
authors.forename: Néstor F
authors.initials: NF
authors.lastname: Aguirre
authors.forename: Pablo
authors.initials: P
authors.lastname: Villarreal
authors.forename: Gerardo
authors.initials: G
authors.lastname: Delgado-Barrio
authors.forename: Edwin
authors.initials: E
authors.lastname: Posada
authors.forename: Andrés
authors.initials: A
authors.lastname: Reyes
authors.forename: Malgorzata
authors.initials: M
authors.lastname: Biczysko
authors.forename: Alexander O
authors.initials: AO
authors.lastname: Mitrushchenkov
authors.forename: María Pilar
authors.initials: MP
authors.lastname: de Lara-Castells
mesh_terms: D004583:Electrons; D006371:Helium / Q000737:chemistry*; D006859:Hydrogen / Q000737:chemistry*; D006860:Hydrogen Bonding; D015394:Molecular Structure; D011789:Quantum Theory
chemical_list: D006371:Helium; D006859:Hydrogen