Theoretical studies of the (X)over-tilde 2Π and (A)over-tilde 2Σ+ states of the He•OH and Ne•OH complexes

Potential energy surfaces for the (X) over tilde (2)Pi and (A) over tilde (2)Sigma(+) states of the He . OH and Ne . OH complexes have been developed, using the restricted open-shell coupled cluster [RCCSD(T)] method. These potentials have been used to calculate rotation-vibration energies for both electronic states of these complexes and their deuterated analogs. Good agreement with the available experimental vibrational energies and rotational constants is obtained. In spite of being relatively weakly bound, the vibrational eigenstates for both electronic states of these species display significant deviations from the simple zero-order free-rotor/anharmonic oscillator limit, leading to potentially rich spectra. (C) 2000 American Institute of Physics. [S0021-9606(00)30138-6].