Spectroscopic Characterizations and DFT Calculations of Olanzapine: Thermochemistry, HOMO-LUMO, FT-IR, MEP, and Hirshfeld Surface (HS) Analyses

Olanzapine (OZ) was investigated quantum chemically using the Density Functional Theory (DFT) approach, and its surface was analyzed spectrochemically. To obtain the optimized structure, which serves as the basis for all other calculations, the LanL2DZ basis set was used. The DFT method has been employed to investigate the analysis of the title compound, specifically focusing on its ground state, which corresponds to the minimum energy state. The highest occupied molecular orbital (HOMO) and the lowest unoccupied molecular orbital (LUMO) energy levels of the frontier orbitals were obtained. The energy gap between HOMO and LUMO orbitals was determined to be 3.937 eV. HOMO-LUMO band gap (BG) emphasizes that adequate charge transfer has occurred within the molecule. In this context, Molecular Electrostatic Potential (MEP) surface analysis was investigated, and thermochemical properties of OZ (C17H20N4S-molecular formula) were obtained and reported. The Hirshfeld surfaces including di, de, dnorm, shape index, curvedness, and fragment patch of C17H20N4S were pictured and discussed.