study of electronic structure of lithium attachment

In this work, the ionization energies and electronic structures of several important conformers of ascorbic acid with lithium were studied in the gas phase, theoretically# thermochemistry calculations were performed on all possible conformers and the stable conformers were selected for the ionization energies for two cases vitamin c and lithium attachment of them# symmetry adapted cluster/configuration interaction methodology employing the single and double excitation operators (sac-ci sd-r) along with a 6-311g++(d,p) basis set were used for the calculations# natural bonding orbital (nbo) calculations have been performed for five first ionization bands involved in the ionization process# these calculations showed that the first ionization band of both forms, vitamin c and li+vitamin c were related to the  electrons of c=c bond of the ring in the structure of the molecule# although, there were the lone electron pairs of oxygen atoms and  electrons of c=o bond in the molecule# other ionization bands have different characters for two forms# in the lithium attachment structures, ionization does not take place from some oxygen atoms because of they have interaction with lithium#