نتایج جستجو برای: hückel model
تعداد نتایج: 2104715 فیلتر نتایج به سال:
Benzene represents the showcase of Hückel aromaticity. The silicon analog, hexasilabenzene, has consequently been targeted for decades. We now report an intensely green isomer of Si6R6 (R being 2,4,6-triisopropylphenyl) with a tricyclic structure in the solid state featuring silicon atoms with two, one, and no substituents outside the ring framework. The highly dispersed 29Si nuclear magnetic r...
It is shown that a very simple semiempirical equation represents quite accurately the thermodynamic properties of aqueous sodium chloride from 373 to 823 K. The equation comprises one Margules term and a Debye-Hückel term. Just the one Margules parameter is freely adjustable because the Debye-Hückel parameter is determined by the properties of water. The equation is valid from the saturation co...
The interpretation of topological resonance energy (TRE), the mathematical measure of energetic chemical aromaticity at the Hückel level of theory, is revisited by providing a concise analysis of the matching polynomial of a chemical graph. Whereas the matching (or acyclic) polynomial is not a properly characteristic polynomial in general, it is the arithmetic mean of the characteristic polynom...
Dense suspensions of small strongly interacting particles are complex systems that are rarely understood on the microscopic level. We investigate properties of dense suspensions and sediments of small spherical Al2O3 particles in a shear cell by means of a combined molecular-dynamics and stochastic rotation dynamics simulation. We study structuring effects and the dependence of the suspension's...
A direct connection is established between three-dimensional aromatic closo boron hydride clusters and planar aromatic [n]annulenes for medium and large boron clusters. In particular, the results prove the existence of a link between the two-dimensional Hückel rule, as followed by aromatic [n]annulenes, and Wade-Mingos' rule of three-dimensional aromaticity, as applied to the aromatic [Bn Hn ](...
New model equations are derived for dynamics of self-aggregation of finite-size particles. Differences from standard Debye-Hückel [1] and Keller-Segel [2] models are: a) the mobility μ of particles depends on the locally-averaged particle density and b) linear diffusion acts on that locally-averaged particle density. The cases both with and without diffusion are considered here. Surprisingly, t...
Much progress has been achieved on quantitative assessment of electrostatic interactions on the all-atom level by molecular mechanics and dynamics, as well as on the macroscopic level by models of continuum solvation. Bridging of the two representations-an area of active research-is necessary for studying integrated functions of large systems of biological importance. Following perspectives of ...
The model under consideration is a two-dimensional two-component plasma, i.e., a continuous system of two species of pointlike particles of opposite charges ±1, interacting through the logarithmic Coulomb interaction. Using the exact results for the form-factors of an equivalent Euclidean sine-Gordon theory, we derive the largedistance behavior of the pair correlation functions between charged ...
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