Quantum Theory of Atoms in Molecules Charge-Charge Flux-Dipole Flux Models for the Infrared Intensities of X2CY (X = H, F, Cl; Y = O, S) Molecules

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• 作者：Sergio H. D. M. Faria ; Joã ; o Vi&ccedil ; ozo da Silva Jr. ; Roberto L. A. Haiduke ; Luciano N. Vidal ; Pedro A. M. Vazquez ; Roy E. Bruns
• 刊名：Journal of Physical Chemistry A
• 出版年：2007
• 出版时间：August 16, 2007
• 年：2007
• 卷：111
• 期：32
• 页码：7870 - 7875
• 全文大小：72K
• 年卷期：v.111,no.32(August 16, 2007)
• ISSN：1520-5215

文摘

The molecular dipole moments, their derivatives, and the fundamental IR intensities of the X₂CY (X = H, F,Cl; Y = O, S) molecules are determined from QTAIM atomic charges and dipoles and their fluxes at theMP2/6-311++G(3d,3p) level. Root-mean-square errors of ±0.03 D and ±1.4 km mol^-1 are found for themolecular dipole moments and fundamental IR intensities calculated using quantum theory of atoms inmolecules (QTAIM) parameters when compared with those obtained directly from the MP2/6-311++G(3d,3p)calculations and ±0.05 D and 51.2 km mol^-1 when compared with the experimental values. Charge (C),charge flux (CF), and dipole flux (DF) contributions are reported for all the normal vibrations of these molecules.A large negative correlation coefficient of -0.83 is calculated between the charge flux and dipole fluxcontributions and indicates that electronic charge transfer from one side of the molecule to the other duringvibrations is accompanied by a relaxation effect with electron density polarization in the opposite direction.The characteristic substituent effect that has been observed for experimental infrared intensity parametersand core electron ionization energies has been applied to the CCFDF/QTAIM parameters of F₂CO, Cl₂CO,F₂CS, and Cl₂CS. The individual atomic charge, atomic charge flux, and atomic dipole flux contributions areseen to obey the characteristic substituent effect equation just as accurately as the total dipole moment derivative.The CH, CF, and CCl stretching normal modes of these molecules are shown to have characteristic sets ofcharge, charge flux, and dipole flux contributions.