ab initio study & density functional investigational of adenine & thymine; comparison of primitive gaussian and nbo calculation

we have performed quantum-chemical ab initio in various basis sets at the hartree-fock andb3lyp levels for adenine and thymine with the program gaussian98. the dipole,quadrupole, octapole and hexadecapole moments and primitive in nine basis sets for thesemolecules are presented. the most stabilized forms of these molecules are observed in 6-311++g** basis set. we have evaluated coefficient hybridation of bonds and occupancy orbital,donor and acceptors. nbo calculations show that hybridation of coefficient and occupancy inseveral basis sets is different.