| Abstract
| - The ionization of phenol−water and phenol−ammonia complexeshave been determined both using ab initiomethods that include electron correlation and the hybridthree-parameter B3LYP density functional method.The most stable structure of phenol−water cation corresponds totheC6H5OH+−H2Onon-proton-transferredcomplex. However, for the phenol−ammonia cation the calculationsindicate that the only minimum on thepotential energy surface corresponds to theC6H5O−NH4+ protontransferred form. The computed B3LYPadiabatic ionization potentials forC6H5OH−H2O andC6H5OH−NH3 have beendetermined to be 7.65 and7.33 eV, respectively. The results obtained indicate that, for theneutral H-bonded systems, the B3LYP densityfunctional method yields very similar results to those obtained withthe ab initio MP2 or MCPF methods.However, for the ionized radical cations, B3LYP results comparemuch better with experiment and to theMCPF method than UMP2. The unscaled B3LYP vibrational frequenciesare in very good agreement withthe known experimental data.
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