A theoretical study of ZnH₂: a case of very strong Darling–Dennison resonance

Abstract

The metastable linear ZnH₂ molecule in its X electronic ground state has been investigated by the coupled cluster method CCSD(T) in conjunction with a small-core pseudopotential for the zinc atom. Using three pieces of spectroscopic information for the most abundant isotopomer ⁶⁴ZnH₂, an accurate near-equilibrium potential energy function (PEF) has been constructed and used in variational calculations of rovibrational energies and wave functions. The ν₁ and ν₂ band origins (in cm⁻¹) for ⁶⁴ZnH₂ and ⁶⁴ZnD₂ (in parentheses) are predicted at 1886.4(1349.7) and 635.1(459.8), respectively. ⁶⁴ZnH₂ is characterised by strong Darling–Dennison and l-type rotational resonances. Various perturbations are analysed in detail, partly making use of calculated expectation values of the vibrational quantum number |l|. Einstein coefficients of spontaneous emission are predicted for several transitions.

Keywords:

• ZnH₂
• Coupled Cluster
• Pseudopotentials
• Rovibrational states
• Infrared intensities

Acknowledgements

Financial support by the Fonds der Chemischen Industrie is gratefully acknowledged. We thank the Gesellschaft für wissenschaftliche Datenverarbeitung Göttingen (GWDG) for providing computer time.

Note:

Supplementary material is available to view online.