title: HM⁺ and HM⁺‑He (M = Group 2 metal): chemical or physical interactions?
abstract: We investigate the HM(+)‑He complexes (M = Group 2 metal) using quantum chemistry. Equilibrium geometries are linear for M = Be and Mg, and bent for M = Ca-Ra; the explanation for this lies in the differing nature of the highest occupied molecular orbitals in the two sets of complexes. The difference primarily occurs as a result of the formation of the H-M(+) bond, and so the HM(+) diatomics are also studied as part of the present work. The position of the He atom in the complexes is largely determined by the form of the electron density. HM(+)…He binding energies are obtained and are surprisingly high for a helium complex. The HBe(+)…He value is almost 3000 cm(-1), which is high enough to suspect contributions from chemical bonding. This is explored by examining the natural orbital density and by population analyses.
authors.affiliation: School of Chemistry, University of Nottingham, University Park, Nottingham NG7 2RD, United Kingdom.
authors.forename: Joe P
authors.initials: JP
authors.lastname: Harris
authors.affiliation: School of Chemistry, University of Nottingham, University Park, Nottingham NG7 2RD, United Kingdom.
authors.forename: Hannah
authors.initials: H
authors.lastname: Dodson
authors.affiliation: Department of Chemistry, University of Utah, Salt Lake City, Utah 84112, USA.
authors.forename: W H
authors.initials: WH
authors.lastname: Breckenridge
authors.affiliation: School of Chemistry, University of Nottingham, University Park, Nottingham NG7 2RD, United Kingdom.
authors.forename: Timothy G
authors.initials: TG
authors.lastname: Wright