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1.
Potential energy functions suitable for the (Cs1–xNaxT2O4)-A type zeolite family were obtained from the known crystal structure of Cs7Na5-A zeolite. Using these potential functions, several other crystal structures in these family were obtained by molecular mechanical calculations. The activation energy - to -cage transmission of the H2 molecule and the void volume of Cs3Na9-A zeolite were calculated. 相似文献
2.
Abstract A new Monte Carlo sampling scheme, namely High Directional Monte Carlo procedure, is used to obtain the global energy minimum conformations of polypeptides such as enkephalin and melittin. The resultant structures of enkephalin and melittin agree well with previous results of theoretical and experimental studies. Particularly, it is shown that some important parts in the conformation, such as the hinge region that principally determines the tertiary structure of proteins, are correctly described by the new method. The resultant structures are compared with those of other works and their stereoscopic views are shown. 相似文献
3.
On the Reaction Mechanism of the Complete Intermolecular O2 Transfer between Mononuclear Nickel and Manganese Complexes with Macrocyclic Ligands 下载免费PDF全文
Dr. Jhon Zapata‐Rivera Prof. Rosa Caballol Dr. Carmen J. Calzado Dr. Dimitrios G. Liakos Prof. Frank Neese 《Chemistry (Weinheim an der Bergstrasse, Germany)》2014,20(41):13296-13304
The recently described intermolecular O2 transfer between the side‐on Ni‐O2 complex [(12‐TMC)Ni‐O2]+ and the manganese complex [(14‐TMC)Mn]2+, where 12‐TMC and 14‐TMC are 12‐ and 14‐membered macrocyclic ligands, 12‐TMC=1,4,7,10‐tetramethyl‐1,4,7,10‐tetraazacyclododecane and 14‐TMC=1,4,8,11‐tetramethyl‐1,4,8,11‐tetraazacyclotetradecane, is studied by means of DFT methods. B3LYP calculations including long‐range corrections and solvent effects are performed to elucidate the mechanism. The potential energy surfaces (PESs) compatible with different electronic states of the reactants have been analyzed. The calculations confirm a two‐step reaction, with a first rate‐determining bimolecular step and predict the exothermic character of the global process. The relative stability of the products and the reverse barrier are in line with the fact that no reverse reaction is experimentally observed. An intermediate with a μ‐η1:η1‐O2 coordination and two transition states are identified on the triplet PES, slightly below the corresponding stationary points of the quintet PES, suggesting an intersystem crossing before the first transition state. The calculated activation parameters and the relative energies of the two transition sates and the products are in very good agreement with the experimental data. The calculations suggest that a superoxide anion is transferred during the reaction. 相似文献
4.
Alberto Gonz��lez-Castrillo Jhon Fredy P��rez-Torres Alicia Palacios Fernando Mart��n 《Theoretical chemistry accounts》2011,128(4-6):735-742
A time-dependent theoretical method is used to describe a UV pump?CUV probe strategy to trace, at a femtosecond time scale, the motion of vibrational wave packets created in excited states of the hydrogen molecule by measuring single ionization probabilities. We use a spectral method to solve the time-dependent Schr?dinger equation in full dimensionality, including correlation and all electronic and vibrational degrees of freedom. A pump pulse initially creates a vibrational wave packet in the intermediate electronic excited states of $\hbox{H}_2$ . The frequency of the probe is chosen to ionize the target leaving the ion in a bound vibrational state. By varying the time delay between pulses, non-dissociative single ionization is enhanced or suppressed. Energy differential ionization probabilities are reported and compared with a model based on the Franck?CCondon approximation. 相似文献
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We propose and demonstrate a photonic phase shifter based a on vector-sum technique that uses polarization-maintaining fibers (PMFs). We achieved a continuous and full phase shift up to 2pi at 30.48 GHz by controlling the polarization state of the light injected into two pieces of PMF of different lengths and applying two different modulator bias voltages. 相似文献
8.
Surface-conductive particles consisting of a poly(methyl methacrylate) (PMMA) core and a polyaniline (PA)-coated shell were synthesized and adopted as suspended particles for electrorheological (ER) fluids. The PA-PMMA composite particles synthesized were monodisperse and spherical in shape. The PA-PMMA suspensions in silicone oil showed typical ER characteristics under an applied electric field. The PA-PMMA composite particles possess a higher dielectric constant and conductivity than the pure PA particle, within an acceptable conductivity range for ER fluids, but the PA-based ER fluid showed larger shear-stress enhancement than the PA-PMMA-based systems. This phenomena can be explained by the interfacial polarizability of PA-based ER fluids, which is the difference between the ER fluid's dielectric constant and loss factor - this polarizability was higher than that of PA-PMMA-based ER fluids, as shown by the dielectric spectrum of each fluid. The insulating PMMA core suppressed the interfacial polarization in ER fluids, resulting in reduced interaction among particles under an imposed electric field. 相似文献
9.
Normal mode calculation of A-type zeolite was carried out with the potential energy functions obtained from the constraint method. Mass-weighted cartesian coordinates and the pseudo-lattice method were used. The assignments of IR absorption bands were made with the calculated normal modes, by using the calculated absorption intensities of the modes and the degrees of contribution of the internal coordinates to the modes. The force constants of internal coordinate motions within the framework were also calculated and are compared with the empirical values. 相似文献
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