Calculation of the Electronic Properties Phthalocyanine (H2Pc), Silicon Phthalocyanine (Sipc), Phosphorus Phthalocyanine (PPc) and Energy Gap by the AM1 Method

Abstract

Many semi-empirical methods are available in Gaussian 16. This patch enables analytical gradients and frequencies in addition to increasing efficiency by replacing the code from MOPAC open source, AM1 and PM3 technologies. In the case of a pure molecule, the values of total energy, bond energy, electronic energy, and nuclear energy (-170.893, -1496.855, -4332.708, 45) Kcal/mol have been successively added. After adding Si and P to the free Phthalocyanine molecule, the values transformed to (-133.30, -4987.486, -1294.027, 11.607) Kcal/mol. For the two resulting molecules (PcSi and PcP), the values became (-136.108, -4858.63, -9354.14, 79.930) Kcal/mol. Notably, the first number indicated an increase. Specifically, for total energy numbers, there was a decrease from -170.893 to -133.3 Kcal/mol when adding Si, and a decrease to -136.108 Kcal/mol when adding P. Overall, the energy value increased with both additions, but the bonding energy notably decreased with Si (-1496.855 to -4987.486 Kcal/mol) and P (-4858.63 Kcal/mol). Electronic energy increased from -4332.708 to -1294.027 Kcal/mol when Si was added. Nuclear energy decreased from 45.036 to 11.607 Kcal/mol when Si was added (increasing to 79.930 Kcal/mol with P). The Heat of Formation (H.o.F.) in Kcal/mol equaled 1565.04 when P was added, 1193.384 when Si was added, and 1531.528 when P was added again. The substantial impact of silicon on Phthalocyanine was evident. Furthermore, the dipole moment of the Phthalocyanine molecule, initially at D 3.687, decreased to D 2.093 and D 4.137 when Si was added first and P the second time, showcasing the significant impact of P due to its high atomic number. Determining the HOMO and LUMO and computing the values of Wavenumber, Wavelength, and Symmetry for the three molecules provided a clear illustration. The computation of electrical potential, electronic orbitals, and energy gap revealed an electronic density of 0.346 eV in the case of the free molecule H2Pc, 5.006 eV in the molecule PPc, and 5.660 eV in the case of SiPc. This offers a comprehensive understanding of the impact of adding P and Si to H2Pc.