Ionization energies, electron affinities, and absorption spectrum of fullerene C 60 calculated with the semiempirical HAM/3 and CNDO/S methods

Abstract

Ionization energies (PES), excitation energies (UV) and electron affinities (EA) of fullerene C 60 have been calculated with the semiempirical HAM/3 method. The first few ionization energies calculated with HAM/3 show errors as great as 1.4 eV. The HAM/3-CI method has reproduced the observed UV spectrum fairly well. The HAM/3-Δε method has given fairly good energies for the forbidden lowest singlet and triplet transitions but rather poor results for the allowed transitions. The correlation between calculated PES, UV and EA values is discussed. A method to estimate accurate electron affinity is proposed. The CNDO/S method, on the other hand, has given good values for some of the ionization energies and electron affinities.