Theoretical Study of the MgH Molecule

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Abstract
Within the Born–Oppenheimer framework, extended configuration‐interaction calculations, involving the use of natural orbitals, are carried out to study the ground‐state energy, wavefunction, and selected molecular properties at the experimental equilibrium internuclear separation of the MgH molecule. Electronic population analysis of the elaborate molecular wavefunctions is done to investigate the nature of the chemical bond involved. More limited configuration‐interaction calculations are also carried out to study the low‐lying excited states of the MgH molecule. Potential‐energy curves are plotted, and transition probabilities are also considered. An estimated dissociation energy of 2.0 ± 0.2 eV has been deduced for the MgH molecule. A dipole moment of − 0.595 a.u. (− 1.511 D) was also obtained. The various results obtained confirmed the intuitive belief that the BeH and the MgH molecules are cogeners. Careful analysis of the accurate molecular wavefunctions reveals that the promotion of an s electron to the corresponding p orbital in bond formation is characteristic of the BeH and the MgH molecules. The calculated transition energy (A 2 Π → X 2 Σ + ) for the MgH molecule was within 5% of the experimental value.