نتایج جستجو برای: semiempirical methods
تعداد نتایج: 1875417 فیلتر نتایج به سال:
Invitro antioxidant activity and Molecular modeling studies of nine chromone derivatives optimize their inhibitory activity against Poly [ADP correlated to different molecular properties. The AM1and PM3 semiempirical methods are used to estimate vertical ioniz tion potentials (IPv’s), electron affinity (EA tion coefficient (LogP), hydration energ regression analysis are proposed. The leave fina...
Semiclassical methods for non-adiabatic dynamics simulations, based on a semiempirical diatomics-in-molecules model of intracluster interactions and the mean-field dynamical approach with the inclusion of quantum decoherence, have been used to study the photodissociation of argon cluster cations, Ar(N)(+)(N = 6-19), at E(phot) = 2.35 eV. Time periods upto t = 200 ps have been considered and abu...
A novel method for the synthesis of bile acid derivatives has been developed using "click chemistry". Intermolecular 1,3-dipolar cycloaddition of the propargyl ester of bile acids and azide groups of 1,3,5-tris(azidomethyl)benzene gave a new quasi-podands with 1,2,3-triazole rings. The structures of the products were confirmed by spectral (1H-NMR, 13C-NMR, and FT-IR) analysis, mass spectrometry...
Nanoelectrochemical experiments using detection based on tip enhanced Raman spectroscopy (TERS) show a broad distribution of single-molecule formal potentials E°' for large π-conjugated molecules; theoretical studies are needed to understand the origins of this distribution. In this paper, we present a theoretical approach to determine E°' for electrochemical reactions involving a single molecu...
In molecular simulations with fixed-charge force fields, the choice of partial atomic charges influences numerous computed physical properties, including binding free energies. Many molecular mechanics force fields specify how nonbonded parameters should be determined, but various choices are often available for how these charges are to be determined for arbitrary small molecules. Here, we comp...
Using a semiempirical approach, we show that modified gravity affects the internal properties of terrestrial planets, such as their physical characteristics core, mantle, and core–mantle boundary. We also apply these findings for modeling two-layer exoplanet in Palatini f(R) gravity.
The electroluminescence from PPV and the blue light emission from PPP constitute exciting subjects of study. The band gap of these semiconducting polymers can be engineered in a wide range from red to ultraviolet by structural changes made on them. In the present work, we present a theoretical approach based on semiempirical and ab initio total energy and force calculations of PPV and PPP. We p...
The notion of formal atomic charges in molecules is probably the most debated issue in quantum chemistry. Although atomic charge can not be rigorously defined in a unique way, conclusive evidence is given here which shows that it provides semiquantitative information about a number of molecular properties in a very simple and transparent way. In particular, the calculations of ESCA chemical shi...
Three biologically active conformers of retinal, all-trans, 9and 13-cis, and their Schiff bases (SB), are studied using a combination of electroabsorption (Stark) spectroscopy and semiempirical calculations. All of the retinal isomers studied show both a large change in dipole moment between the ground and excited states (|∆μ| greater than 8 D) and a large change in polarizability between the g...
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