Ab initio electronic and rovibrational structure of MgH22+

The electronic structure of the ground state of MgH22+ has been investigated using relativistically-corrected CCSD(T) in conjunction with ANO-RCC (Mg) and aug-cc-pVQZ (H) basis sets. The MgH22+ molecular potential energy surface possessed minima corresponding to both 1A1 and 1Σg+ equilibrium structures (with a 1Σ+ transition state). The 1A1 structure possessed Re and θe values of 2.0297 A and of 22.09o, respectively. The higher-energy 1Σg+ structure exhibited an Re value of 2.1658 A. Property surfaces were constructed to calculate rovibrational energies and spectral line intensities for the ground states of (1A1)MgH22+, (1A') MgHD2+ and (1A1)MgD22+. For the vibration ground state of (1A1)MgH22+, the vibration-averaged Re and θe values were calculated to be 2.0209 A and 22.53o, respectively. The A, B and C rotational constants were calculated to be 58.0, 2.21 and 2.11 cm-1, respectively