Representative atomic and molecular systems, including various inorganic and organic molecules with covalent and ionic bonds, have been studied by using density functional theory. The calculations were done with the commonly used exchange-correlation functional B3LYP followed by a comprehensive analysis of the calculated highest-occupied and lowest-unoccupied Kohn-Sham orbital (HOMO and LUMO) e...

Along the series of H–AHn bonds, with AHn = CH3, NH2, OH, and F, the bond dissociation energies show a steady increase as can be expected from the increasing difference in electronegativity along this series. However, in the same series for CH3– AHn the bond strength first decreases from CH3–CH3 to CH3–NH2 and only thereafter increases again along CH3–NH2, CH3–OH and CH3–F. To understand the or...

The influence of halogen substituents on the catalytic oxidation of 2,4,6-trihalogenated phenols (TrXPs) by iron(III)-porphyrin/KHSO₅ catalytic systems was investigated. Iron(III)-5,10,15,20-tetrakis(p-hydroxyphenyl)porphyrin (FeTHP) and its supported variants were employed, where the supported catalysts were synthesized by introducing FeTHP into hydroquinone-derived humic acids via formaldehyd...

The Hellmann-Feynman theorem, when applied to nuclear coordinates in a molecular system, states that Feynman forces, i.e. forces acting on a nucleus in a molecule, are solely of an electrostatic nature. This theorem is described by Slater as "the most powerful" theorem applicable to molecules. However, its possibilities have hardly been harnessed. This work presents the use of the Hellmann-Feyn...

Piperine is a natural cytotoxic agent aware of various therapeutic acts. The aim this study to look into the effects solvent polarity on solvent-free energy, dipole moment, polarizability, and hyper-polarizability first order, as well molecular properties including chemical hardness softness, potential, electronegativity, electrophilicity index, in order gain better understanding its reactivity...

Abstract Betahistine serves as a medicament widely used in curing some diseases related to the nervous system. Its molecular properties have been studied by ab initio MO-LCAO-SCF method followed correction electron correlation (MP2) vacuo well water solvent. The chemical potential (electronegativity) and hardness were verified valuable descriptors compared with structurally analogous species.