The resonance theory is still very useful in understanding the valence electron structure. However, such a viewpoint not usually obtained by general-purpose quantum chemical calculations, instead requires rather special treatment as bond methods. In this study, we propose method based on second quantization to analyze results calculations from local point of view electronic structure and diazad...

The inhibiting effect of methionine and tyrosine on the corrosion of iron is researched electrochemically in 0.1M HCl, Quantum chemical calculations were performed. The level of HF with the 6–311G(d,p) basis set for methionine and tyrosine. Corrosion current density has been determined by polarization measures and the inhibition effect was calculated. With an increase in the concentration of in...

Based on work reported by several authors, one of us (RP) has introduced a Mulliken-like population analysis of pair densities. This scheme, introduced first at the semi-empirical level, was subsequently generalised both for SCF and for post-SCF ab initio methods. A potential problem is the basis set dependence that can be expected for all kinds ofMulliken-like approaches. The main purpose of t...

It is discussed that the L€ owdin atomic populations (atomic populations computed in a L€ owdin-orthogonalized basis) are invariant only under unitary transformations of the basis orbitals centered on the same atom, but not under the general rotationalhybridizational transformations as are the Mulliken populations. As a consequence, if basis sets containing 6 d-orbitals (or 10 f-orbitals, etc.)...

The effects of substituents on the pKas of a set of 16 substituted benzoic acids have been examined using density functional theory [B3LYP/6-311G(d, p)] calculations. A variety of quantum chemical parameters were examined as indicators for the variations observed in the experimental pKas, including the Löwdin, Mulliken, AIM, and natural population analysis charges (QL, QM, QA, and Qn) on atoms ...

S. S. Kurtz, Jr., Chairman; P. D. Bartlett, Vice-Chairman 17 June E. Bright Wilson, Jr., "Infrared and Raman Spectra." R. S. Mulliken, "Iltraviolet Absorption Spectra." 18 June G. W. Wheland, "Theory of the Chemical Bond and Resonance in Hydrocarbons." P. D. Bartlett, "Report of Committee on Future Policy of Conference on Petroleum Chemistry at Gibson Island." L. S. Kassel, "Isomerization Equil...

The Pipek-Mezey scheme for generating chemically intuitive, localized molecular orbitals is generalized to incorporate various ways of estimating the atomic charges, instead of the ill-defined Mulliken charges used in the original formulation, or Löwdin charges, which have also been used. Calculations based on Bader, Becke, Voronoi, Hirshfeld, and Stockholder partial charges, as well as intrins...

A new approach for performing Particle Mesh Ewald in ab initio quantum mechanical/molecular mechanical (QM/MM) simulations with extended atomic orbital basis sets is presented. The new approach, the Ambient-Potential Composite Ewald (CEw) method, does not perform the QM/MM interaction with Mulliken charges nor electrostatically fit charges. Instead the nuclei and electron density interact direc...