Molecular geometries and energetics of metal-containing systems using an improved ASED-MO model: a systematic test to group 1 and 2 metal containing systems in the gas phase Original Research Article

Accurate potential energy curves for highly polar metal-containing systems of the group 1 and 2 metals have been calculated by an improved ASED-MO model. The major components of the improvements consist of the addition of an intramolecular Madelung-type potential to the Born-Oppenheimer energy, accounting for the electrostatic attractive interactions between the charged atoms in the molecule and the usage of Slater-type orbital exponents dependent on the atomic net charges. The new computational scheme has successfully been applied in predicting the structural and energetic parameters of the whole series of the neutral and ionic (cationic and anionic) group 1 and 2 metal oxide diatomics in both their ground and selected low-lying electronic states, as well as the corresponding series of the metal monohydroxides. The importance of the inclusion of the intramolecular Madelung-type potential for the satisfactory description of a highly ionic bonding has been demonstrated by applying the new theoretical model on the series of the “unknown” molecule/dipole CH4·MO and CH4·MO+ ( M = Be, Mg, Ca, Sr and Ba) complexes involving both a highly ionic M-O and a very weak Van der Waals type CH4⋯MO interactions.