Theoretical determination of electron affinity and ionization potential ofDNA and RNA bases

The ionization potentials and electron affinities of thymine, cytosine, ade nine, guanine, and uracil were determined at density functional level using different exchange-correlation functionals and basis sets. Results showed that the computed ionization potentials are very close to the experimental counterparts. The sign of adiabatic electron affinities of adenine, thymine , and uracil is unaffected by the used level of theory while that for guani ne and cytosine depends on both the used potential and basis set. Vertical electron affinities are always negative in agreement with the experimental indications. (C) 2000 John Wiley & Sons, Inc.