AM1 and PM3 provide nearly closed arrangement for the activity of the studied molecules with respect to the calculated values of the energy of the highest occupied molecular orbital
. Although AM1 uses the same basic approximation as MNDO, AM1 has a different trend than MNDO.
However, the the Energy of the Highest Occupied Molecular Orbital
([E.sub.HOMO]) and the total energy for the reaction products in Table 1 reveal that the product has more stability, in this state the product new buckyball [C.sub.84][H.sub.2] (IV), most stable among the four new buckyballs, was [C.sub.84][H.sub.2] (IV) with an increase in the Ehomo, that is (-0.5197 eV), (-0.4968 eV), and (-0.6955 eV) relative to [C.sub.84][H.sub.2] (I), [C.sub.84][H.sub.2] (II), and [C.sub.84][H.sub.2] (III), respectively.
The electronic properties such as highest occupied molecular orbital
([E.sub.HOMO]) energy, lowest unoccupied molecular orbital ([E.sub.LUMO]) energy, and the energy gap ([E.sub.g] = [E.sub.LUMO] - [E.sub.HOMO]), the dipole moment ([mu]) were calculated.
The aim of our calculation is to calculate the following quantum chemical indices: the energy of highest occupied molecular orbital
([E.sub.HOMO]), the energy of lowest unoccupied molecular orbital ([E.sub.LUMO]), energy gap ([DELTA]E), hardness ([eta]), softness ([omega]), electrophilicity index ([omega]), the fraction of electrons transferred ([DELTA]N) from inhibitor molecule to the metal surface, and energy change when both processes occur, namely, charge transfer to the molecule and backdonation from the molecule ([DELTA][E.sub.backdonation]), and correlate these with the experimental observations.