Ab initio potential energy surfaces, bound states, and electronic spectrum of the Ar-SH complex.

New ab initio potential energy surfaces for the (2)Pi ground electronic state of the Ar-SH complex are presented, calculated at the RCCSD(T)/aug-cc-pV5Z level. Weakly bound rotation-vibration levels are calculated using coupled-channel methods that properly account for the coupling between the two electronic states. The resulting wave functions are analyzed and a new adiabatic approximation including spin-orbit coupling is proposed.

Ab initio potential energy surfaces for excited electronic states of the molecular ion HCN+.

Potential energy surfaces for the linear X2Pi, 2(2)Pi, A2Sigma+ , B2Sigma+, 3(2)Sigma+, 1(4)Pi and 1(4)Sigma+ states and for the bent B2Sigma+/3(2)A' state of HCN+ have been calculated by a multi-reference configuration interaction (MRCI) method. The persistence of vibrational structure in the photoelectron spectrum of the B state above the experimental dissociation asymptote is interpreted in terms of a local maximum on the potential energy surface with respect to stretching the CH bond. The global minimum for this state has a bent geometry with a bond angle of 129 degrees.