Adenosine Triphosphate (ATP) is one of the most important biomolecules. It plays an essential role in hying systems and was extensively investigated by not only experimental methods but theoretical calculations as well. As early as 1960, Fukui et al and Pullman et al. studied the molecule through a simple molecular orbital method (H(?)ckel theory). Although H(?)ckel theory had been applied to ATP molecule, it did not give satisfactory resuhs, as the three-dimensional structure of