Phenol-water(1<or=n<or=3) revisited: an ab initio study on the photophysics of these clusters at the level of coupled cluster response theory.

The S1(pi*<--pi) state surfaces of the phenol-water(1<or=n<or=3) clusters are reexplored at the level of coupled cluster response theory. The global minima for n=2 and n=3 so obtained are qualitatively different from those reported so far, which were obtained with methods such as configuration interaction singles or complete active space self-consistent field lacking dynamical electron correlation effects. Furthermore, the minimum-energy points on the conical intersection seams were located in this work. The results of these calculations offer a qualitative explanation for the anomalous photophysical behavior (broad congested absorption band structure, low quantum yield, short lifetime) of n=2 and the observed predissociation of n=3 at excess energies beyond approximately 100 cm(-1), resolving a disagreement between theory and experiment which persisted for almost a decade.