نتایج جستجو برای: quantum chemical parameters
تعداد نتایج: 1199629 فیلتر نتایج به سال:
Historically, Hammett constants have been extremely effective in describing the influence of substituents on chemical reactivity and other physical and chemical properties, whereas variables derived from quantum chemical calculations have generally been less effective. Taking the experimental pK(a)s of substituted anilines as a representative physicochemical property, five ab initio quantum che...
nanopartmles have been used as an approach to improve the pharmacodynamic and phannacokinetie propertiesof various drues. amino acids have been considered to be useful to make such nano particles because ofthocompatithe and biodegradable characteristic. the quantum mechanical method that was chosen to analyze inethio hexa peptide nano ring]. the structure of some peptide nanorrigs as well as th...
In this research, CdS and PbS quantum dots were applied as the light sensitizers in TiO2 based nanostructured solar cells. The PbS quantum dots could absorb a wide range of the sunlight spectrum on earth due to their low bandgap energy. As a result, the cell sensitization is more effective by application of both CdS and PbS quantum dots sensitizers. The TiO2 nanocrystals were synthesized throug...
Calculations that minimize the energy and optimize the geometry of all atomic coordinates for two proposed kaolinite crystal structures were performed using a first-principles, quantum chemical code based on local density functional theory. All calculations were performed using published unit-cell parameters. Innerand interlayer H atom positions agree well with those determined by Bish (1993) f...
Over the past decade, the chemical behavior of flavonoids as antioxidants has become the subject ofintense experimental research. In this paper, we use a quantum-chemical approach to shed light on thereactivity of four poly phenols, Benzoic acid, vanilic acid, gallic acid and flavone . In order to establishthe most efficient theoretical methodology, different methods, either Hartree—Fock-based ...
The methods of quantitative conformational analysis of cyclic fragments in molecules and the computer program RICON (RIng CONformations) developed by us for this purpose are considered. Program RICON uses atomic coordinates obtained from X-ray studies or force field/quantum chemical computations and allows one to analyze geometric parameters of a molecule, to compute the puckering parameters of...
The SPASIBA force field parameters have been obtained for Fe/Fe-Oxygen interactions occuring between non-heminic iron and hydroxyl groups of polyphenols found in tannins. These parameters were derived from normal modes analyses based on quantum chemical calculations using the Density Functional Theory (DFT). Four models involving complexation of iron with water ([Fe(H2O)6] , [Fe(H2O)6] ) and wi...
abstract nowadaysphotovoltaic solar cells (pvs) areacknowledged the fastest growing energy technology in the word, however, they only account for only fraction of current global renewable energy capacity. it isrecognized that this incomplete market penetration has been largely a result of the technology’sexcessive cost. so researchers are trying to find innovative, economic way with theaim of ...
This paper is concerned with computations whose characteristics are akin to certain unique phenomena that occur in di erent domains of science. We are particularly interested in systems whose parameters are altered unpredictably whenever one of these parameters is measured or modi ed. Examples of such computational environments include those in which Heisenberg's uncertainty principle of quantu...
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