We show that the use of the quantum theory of atoms in molecules (QTAIM) in electronically excited states allows expanding the knowledge that the molecular orbital (MO) framework provides about electronic rearrangements. Despite that historical prejudice seemed to preclude the use of QTAIM beyond the electronic ground state, this paper evidences that QTAIM is versatile enough to deal with excit...

DFT-GGA method of Perdew-Burke-Ernzerhof (PBE) is used with aug-cc-PVTZ, 6-311++G**, and Def2-TZVP large basis sets to study the hydrogen bond interactions between oxygen lone pair as a donor electron with hydrogen atom connected to the aniline’s nitrogen as an electron acceptor (H2O···HNH-Ph), and nitrogen lone pair with hydrogen of water molecule (Ph-H2N···HOH...

Ionic liquids (ILs) have shown excellent performance in the separation of binary azeotropes through extractive distillation [1]. But role ionic liquid azeotropic system is not well understood. In this paper, COSMO-RS model was applied to screen an appropriate IL separate azeotrope ethyl acetate (EA) and ethanol 1-octyl-3-methylimidazolium tetrafluoroborate ([OMIM][BF4]) selected. The Quantum Me...

DPPC (dipalmitoylphosphatidylcholine) and DMPC (dimyristoylphosphatidylcholine) are taken asphospholipids with an equal polar heads and with the difference in the length of hydrocarbonchains. Results obtain from the structural optimization of the isolated DPPC and DMPC in the gasphase, at the Hartree-Fock level of theory by means of STO-3g,3-21G, 6-31G and 6-31G* basissets. the most important d...

In this work, the hydrogenation of acetylene on Pd2/g-C3N4 catalyst is investigated by density functional theory (DFT) and quantum atoms in molecules (QTAIM) calculations. The pre-reactant (R), transition states (TSs), intermediates (IMs), involved process, are characterized from point view energy structure. calculated barriers for hydrogen transfer to ethylene 6.77 12.28 kcal/mol, respectively...

Vibrational modes ascribed to the stretching of X-H bonds from donor monomers (HXdonor) in complexes presenting hydrogen bonds (HF···HF, HCl···HCl, HCN···HCN, HNC···HNC, HCN···HF, HF···HCl and H2O···HF) exhibit large (4 to 7 times) infrared intensity increments during complexation according to CCSD/cc-pVQZ-mod calculations. These intensity increases are explained by the charge-charge flux-dipol...