Adiabatic and quasi-diabatic investigation of the strontium hydride cation SrH⁺: structure, spectroscopy, and dipole moments

Ab initio investigation has been performed for the strontium hydride cation SrH⁺ using a standard quantum chemistry approach. It is based on the pseudopotentials for atomic core representations, Gaussian basis sets, as well as with full configuration interaction calculations. A diabatisation procedure based on the effective hamiltonian theory and an effective metric is used to produce the quasi-diabatic potential energy. Adiabatic and quasi-diabatic potential energy curves and their spectroscopic parameters for the ground and many excited electronic states of ^1,3Σ⁺, ^1,3,Π and ^1,3Δ symmetries have been determined. Their predicted accuracy is discussed by comparing our well depths and equilibrium positions with the available experimental and theoretical results. Moreover, we localized and analyzed numerous avoided crossings between the electronic states of ^1,3Σ⁺ and ^1,3Π symmetries. The correction of the electron affinity of the H atom is also considered, for the 1-10¹Σ⁺ electronic states, to improve the accuracy of the adiabatic potential energies of these states. In addition, we calculated the dipole moments, for a wide range of internuclear distances in both diabatic and quasi-diabatic representations. The adiabatic permanent dipole moments for the 10¹Σ⁺ electronic states revealed ionic characters related to electron transfer and yields both SrH⁽⁺⁾ and Sr⁽⁺⁾H arrangements. The transition dipole moments between neighbor electronic states revealed many peaks around the avoided crossing positions. (author)Ab initio investigation has been performed for the strontium hydride cation SrH⁺ using a standard quantum chemistry approach. It is based on the pseudopotentials for atomic core representations, Gaussian basis sets, as well as with full configuration interaction calculations. A diabatisation procedure based on the effective hamiltonian theory and an effective metric is used to produce the quasi-diabatic potential energy. Adiabatic and quasi-diabatic potential energy curves and their spectroscopic parameters for the ground and many excited electronic states of ^1,3Σ⁺, ^1,3, and ^1,3 Δ symmetries have been determined. Their predicted accuracy is discussed by comparing our well depths and equilibrium positions with the available experimental and theoretical results. Moreover, we localized and analyzed numerous avoided crossings between the electronic states of ^1,3Σ⁺ and ^1,3Π symmetries. The correction of the electron affinity of the H atom is also considered, for the 1-10¹Σ⁺ electronic states, to improve the accuracy of the adiabatic potential energies of these states. In addition, we calculated the dipole moments, for a wide range of internuclear distances in both diabatic and quasi-diabatic representations. The adiabatic permanent dipole moments for the 10¹Σ⁺ electronic states revealed ionic characters related to electron transfer and yields both SrH⁽⁺⁾ and Sr⁽⁺⁾H arrangements. The transition dipole moments between neighbor electronic states revealed many peaks around the avoided crossing positions. (author)