In this research, the potential energy and vibrational frequency of the linear molecule (HF) were studied and calculated using semi-empirical theoretical programs by the (MNDO-PM3) method. The spatial geometric structure of the studied molecule was plotted. The potential energy curve of the molecule was drawn based on the change in bond length (H—F) versus the obtained energy values. From this, the total energy at the equilibrium position was calculated and was (-133.755 eV) at an equilibrium distance of (0.93 Å). From the potential curve, the dissociation energy of the molecule was calculated and found to be (-131.454 eV). Additionally, the energy values of molecular orbitals, including the highest occupied molecular orbital (EHOMO) and the lowest unoccupied molecular orbital (ELUMO), were calculated, with an energy gap of 19.784 eV. From the initial and final matrices, the thermal properties were calculated at varying temperatures between (100-300 K), and the graphical relationship of each property with temperature was plotted. The results were close to previous experimental studies.
M. Ibrahim (Thu,) studied this question.