STRUCTURE AND INTERMOLECULAR MOTIONS OF THE WATER DIMER ANION

The electronic and geometrical structures of the water dimer anion are investigated by density functional calculations. Theoretical values o f the very weak electron affinities and vertical detachment energies s how good agreement with available experimental data. It is predicted t hat a significant modification of the neutral parent geometry is intro duced by the electron attachment process and leads to a large excitati on of anion intermolecular modes. The interpretation of field-detachme nt experiments of (H2O)(2)(-) and (D2O)(2)(-), produced in collisions between laser-excited Rydberg atoms and cold neutral water clusters, c onfirms the existence of large amplitude low-frequency motions in the anions. (C) 1996 American Institute of Physics.