The hydrogen-bonded cluster anions Br-•••HCCH and I-•••HCCH:: results of coupled cluster calculations

Large-scale coupled cluster calculations at the CCSD(T) level of approximation have been carried out for the anionic complexes Br-. . . HCCH and I-. . . HCCH, both of which have a linear equilibrium structure. The equilibrium dissociation energies (D-e) are predicted to be 3126 and 2550 cm(-1), respectively. Agreement with available experimental data, obtained through predissociation infrared spectroscopy, is very good. In addition, many predictions are made for spectroscopic properties of various isotopomers of the two species. Particular emphasis is given to the effects of vibrational anharmonicity, conveniently expressed by anharmonicity constants X-ij and vibration-rotation coupling constants alpha (r). Transition dipole moments were calculated for various stretching vibrational transitions.