Calculation of predissociation resonances for the A 2Σ+ state of HeH with the complex coordinate method in a diabatic Hamiltonian representation

The predissociation lifetimes of the lowest rovibrational levels of the A 2Σ+ state of HeH are computed with the aid of a diabatic Hamiltonian representation obtained by means of a pointwise diagonalization of adiabatic CI quadrupole moment matrices. Complex vibrational energy eigenvalues are computed employing the standard complex coordinate method and related variational principle in conjunction with the diabatic potential and coupling element curves. This procedure is marked by good convergence behaviour for the complex energy eigenvalues and yields lifetime values which are in good agreement with known experimental results for a series of HeH isotopomers without necessitating the computation of non-adiabatic nuclear kinetic energy matrix elements. (author)