A theoretical study of ZnH2, a case of very strong Darling-Dennison resonance

International audienceThe 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 the 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 states and wave functions. The 1 and 2 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 characterized by strong Darling- Dennison and l-type rotational resonances. Various local perturbations are analyzed in detail, making use of calculated expectation values of the vibrational quantum number l. Einstein coefficients of spontaneous emission are predicted for several transitions