نتایج جستجو برای: natural bond orbital

تعداد نتایج: 586710  

Density Functional Theory (DFT) calculations have been carried out using a Polarizable Continuum Model (PCM) in an attempt to investigate the electro-molecular properties of branched-chain glucoside (C14C10-D-glucoside) isomers. The results showed that αconfiguration of pyranoside form is thermodynamically the most stable, while the solution should contain much more β...

2000
Jiali Gao Yirong Mo

A mixed molecular orbital and valence bond (MOVB) method has been developed and applied to chemical reactions. In the MOVB method, a diabatic or valence bond (VB) state is defined with a block-localized wave function (BLW). Consequently, the adiabatic state can be described by the superposition of a set of critical adiabatic states. Test cases indicate the method is a viable alternative to the ...

Journal: :Journal of chemical theory and computation 2006
F Matthias Bickelhaupt Miquel Solà Célia Fonseca Guerra

We have carried out a theoretical investigation of the methylalkalimetal monomers CH3M and tetramers (CH3M)4 with M = Li, Na, K, and Rb and, for comparison, the methyl halides CH3X with X = F, Cl, Br, and I, using density functional theory (DFT) at BP86/TZ2P. Our purpose is to determine how the structure and thermochemistry (e.g., C-M bond lengths and strengths, oligomerization energies) of org...

2013
Vladimir G. Tsirelson Adam I. Stash Valentin V. Karasiev Shubin Liu

In this work, based on the experimental electron density, we present the approximate spatial distributions of the Pauli potential, one of the key quantities in the orbital-free density functional, for three crystalline systems: diamond, cubic boron nitride, and magnesium diboride. Our aim is to reveal a link between the Pauli potential and the orbital-free picture of chemical bond. We also expa...

Journal: :The journal of physical chemistry. A 2007
M J Bell K-C Lau M J Krisch D I G Bennett L J Butler F Weinhold

This study investigates two features of interest in recent work on the photolytic production of the methoxy carbonyl radical and its subsequent unimolecular dissociation channels. Earlier studies used methyl chloroformate as a photolytic precursor for the CH3OCO, methoxy carbonyl (or methoxy formyl) radical, which is an intermediate in many reactions that are relevant to combustion and atmosphe...

2014
MASOOME SHEIkHI MOHAMMAD MAHMOODI

The density functional theory (DFT) calculations at the level of B3LYP/6-31G was carried out on the structure 4(5)-Imidazole-carbaldehyde-N(5)-phenylthiosemicarbazone (ImTPh) in gas phase using Gaussian 03. Dipole moment (Debye), energy of structure formation (HF; kcal/mol) and point group, NMR parameters such as isotropic shielding (σiso) and anisotropic shielding (σaniso), σ11, σ22 and σ33 ob...

2004
Rolf Gleiter Wolf-Dieter Stohrer Roald Hoffmann

Sz~rnmnr~~ . From a molecular orbital study of model systems we derivc the electronic requiremcnts for the Grob fragmentation. The necessary condition for an allowed fragmentation in an ?I-C,-C,-C,-N system, or the amino cation +C,-C,-C,-N is the level ordering A below S . This in turn is set by maximal through-bond coupling of the empty cation orbital and the nitrogen lone pair. The conformati...

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