AB-INITIO CALCULATED ROTATION-VIBRATION LINESTRENGTHS FOR HEH2+

Together with the recently determined potential energy surface for the ground electronic state of HeH2+ [V. Spirko and W. P. Kraemer, J. Mol . Spectrosc. 172, 265-274 (1995)], the electric dipole moment componen ts were calculated directly as expectation values with the correspondi ng length operators at the center of mass of the ion and using the var iationally optimized configuration interaction wavefunctions. From the fitted potential energy and dipole moment functions all bound rotatio n-vibration energy levels and the line strengths of all dipole-allowed bound-bound transitions were evaluated variationally within the frame work of the Sutcliffe-Tennyson Hamiltonian. Strong transitions, especi ally for the (He ... H-2)(+) stretching motion, were obtained in the 5 00-800 cm(-1) infrared frequency range, The present calculations demon strate that the conditions for detecting the still unobserved rotation -vibration spectrum of HeH2+ are rather promising. (C) 1997 Academic P ress.