HM+ and HM+‑He (M = Group 2 metal): chemical or physical interactions?

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...

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Bibliographic Details
Main Authors: Harris, Joe P., Dodson, Hannah, Breckenridge, W.H., Wright, Timothy G.
Format: Article
Published: American Institute of Physics 2014
Online Access:https://eprints.nottingham.ac.uk/28797/
Description
Summary: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.