QUANTUM COMPUTATIONAL STUDIES ON PORPHYCENE - Theoretical and Computational Research in the 21st Century - page 172

9.3.2 AM1 CALCULATIONS

AM1 studies are carried out on pyrrol and porphycene. The eigen values
are for the HOMO, and the LUMO of the molecules studied in this work
is taken as the HOMO and LUMO orbital energies. Using these orbital
energies, we have computed the global reactivity descriptors such as μ, χ,
η, S ,ω for pyrrol and porphycene following Eqs. (1), (7), (8), (4), and (13),
respectively.
The Fukui functions and local softnesses for each site of the pyrrol
and porphycene are computed using the ansatz Eqs. (23-25) and (27-29),
considering the LCAO coeffi cient of each carbon atom. Physical proper-
ties of pyrrol and porphycene (on the basis of AM1 calculation) are also
tabulated. The ZDO atomic charges and Mulliken charges, obtained in this
method for each molecule are also tabulated.

9.4 RESULT AND DISCUSSION

In Table9.1, we have tabulated the computed (on the basis of AM1 calcula-
tion) physical properties of pyrrol andporphycene.

TABLE 9.1 Physical properties of pyrrol and porphycene (on the basis of AM1 calculation)

System Energy (SCF)

(au)

Energy (geometrical)
(au)

Heat of
formation
(kcal/mol)

Total dipole
moment
(Debye)

Pyrrol −28.9101022 −28.911379 40.5046 1.94334174

Porphycene −131.07762072 −131.3313443 257.2120 3.58039015

The computed (on the basis of HMO theory)π charge density, bond
order, and bond length of pyrrol are presented in Tables 9.2(A-C), respec-
tively.

TABLE 9.2 (A) Computed πcharge density of pyrrol on the basis of HMO theory
Atom Pi charge density

P(1,1) 1.03462

P(2,2) 1.10556

P(3,3) 1.10556

P(4,4) 1.03462

P(5,5) 1.71965