DENSITY-FUNCTIONAL THEORY DESCRIPTION OF EXCITED-STATE INTRAMOLECULARPROTON-TRANSFER

Enol to keto conversion in the lowest excited states of three differen t systems with similar OCCNN backbone structures is examined within de nsity functional theory. Excited state proton transfer occurs both wit hin the local spin density approximation and with gradient corrections . The latter approach provides an improved description of intramolecul ar hydrogen bonding and yields results in reasonable agreement with pr evious ab initio calculations for small model systems and with experim ents for practical benzotriazole photostabilizers.