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Available Experimental Data. (available + experimental_data)
Selected AbstractsTheoretical and kinetic study of the H + C2H5CN reactionJOURNAL OF COMPUTATIONAL CHEMISTRY, Issue 6 2010Jingyu Sun Abstract The reaction of H radical with C2H5CN has been studied using various quantum chemistry methods. The geometries were optimized at the B3LYP/6-311+G(d,p) and B3LYP/6-311++G(2d,2p) levels. The single-point energies were calculated using G3 and BMC-CCSD methods based on B3LYP/6-311++G(2d,2p) geometries. Four mechanisms were investigated, namely, hydrogen abstraction, C-addition/elimination, N-addition/elimination and substitution. The kinetics of this reaction were studied using the transition state theory and multichannel Rice-Ramsperger-Kassel-Marcus methodologies over a wide temperature range of 200,3000 K. The calculated results indicate that C-addition/elimination channel is the most feasible over the whole temperature range. The deactivation of initial adduct C2H5CHN is dominant at lower temperature with bath gas H2 of 760 Torr; whereas C2H5+HCN is the dominant product at higher temperature. Our calculated rate constants are in good agreement with the available experimental data. © 2009 Wiley Periodicals, Inc. J Comput Chem, 2010 [source] About the calculation of exchange coupling constants in polynuclear transition metal complexesJOURNAL OF COMPUTATIONAL CHEMISTRY, Issue 8 2003Eliseo Ruiz Abstract The application of theoretical methods based on the density functional theory with hybrid functionals provides good estimates of the exchange coupling constants for polynuclear transition metal complexes. The accuracy is similar to that previously obtained for dinuclear compounds. We present test calculations on simple model systems based on H · · · He and CH2 · · · He units to compare with Hartree,Fock and multiconfigurational results. Calculations for complete, nonmodeled polynuclear transition metal complexes yield coupling constants in very good agreement with available experimental data. © 2003 Wiley Periodicals, Inc. J Comput Chem 24: 982,989, 2003 [source] Molecular simulation of ammonia absorption in the ionic liquid 1-ethyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide ([emim][Tf2N])AICHE JOURNAL, Issue 9 2009Wei Shi Isotherms for ammonia absorption in the ionic liquid 1-ethyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide ([emim][Tf2N]) are computed at temperatures ranging from 298 K to 348 K using osmotic ensemble Monte Carlo simulations. The results agree well with previous experimental measurements. Activity coefficients vary from 0.5 to 0.8, indicating negative deviations from Raoult's Law. The computed enthalpy of mixing ranges from ,2 to ,11 kJ/mol. Computed partial molar volumes are on the order of 25,30 cm3/mol. Energy and radial distribution analyses indicate that ammonia interacts more strongly with the cation than the anion, in contrast to observations made of other gases in ionic liquids such as CO2. The reason for this behavior is that ammonia forms a strong hydrogen bond with the ring hydrogen atoms of the cation. The simulations predict that strategies aimed at changing the solubility of ammonia should focus on altering the hydrogen bond donating ability of the cation, and that altering the anion will have more modest effects. It is shown that this hypothesis is consistent with available experimental data. © 2009 American Institute of Chemical Engineers AIChE J, 2009 [source] Reliability of computational scienceNUMERICAL METHODS FOR PARTIAL DIFFERENTIAL EQUATIONS, Issue 4 2007I. Babu Abstract Today's computers allow us to simulate large, complex physical problems. Many times the mathematical models describing such problems are based on a relatively small amount of available information such as experimental measurements. The question arises whether the computed data could be used as the basis for decision in critical engineering, economic, and medicine applications. The representative list of engineering accidents occurred in the past years and their reasons illustrate the question. The paper describes a general framework for verification and validation (V&V) which deals with this question. The framework is then applied to an illustrative engineering problem, in which the basis for decision is a specific quantity of interest, namely the probability that the quantity does not exceed a given value. The V&V framework is applied and explained in detail. The result of the analysis is the computation of the failure probability as well as a quantification of the confidence in the computation, depending on the amount of available experimental data. © 2007 Wiley Periodicals, Inc. Numer Methods Partial Differential Eq 23: 753,784, 2007 [source] Ab-initio investigation of structural, electronic and optical properties for three phases of ZnO compoundPHYSICA STATUS SOLIDI (B) BASIC SOLID STATE PHYSICS, Issue 9 2007Z. Charifi Abstract The complex density-functional theory (DFT) calculations of structural, electronic and optical properties for the three phases: wurtzite (B4), zincblende (B3) and rocksalt (B1) of ZnO compound have been reported using the full-potential linearized-augmented plane-wave (FP-LAPW) method as implemented in the WIEN2k code. We employed both the local-density approximation (LDA) and the generalized-gradient approximation (GGA), which is based on exchange,correlation energy optimization to calculate the total energy. Also, we have used the Engel,Vosko GGA formalism, which optimizes the corresponding potential for band-structure calculations. The 3d orbitals of the Zn atom were treated as the valence band. The calculated structural properties (equilibrium lattice constant, bulk modulus, etc.) of the wurtzite and rocksalt phases are in good agreement with experiment. The B4 structure of ZnO is found to transform to the B1 structure with a large volume collapse of about 17%. The phase transition pressure obtained by using LDA is about 9.93 in good agreement with the experimental data. B1-ZnO is shown to be an indirect bandgap semiconductor with a bandgap of 1.47 eV, which is significantly smaller than the experimental value (2.45 ± 0.15 eV). While B3 and B1 phases have direct bandgap semiconductors with bandgaps 1.46 and 1.57 eV, respectively. Also, we have presented the results of the effective masses. We present calculations of the frequency-dependent complex dielectric function , (,) and it zero-frequency limit ,1(0). The optical properties of B4 phase show considerable anisotropic between the two components. The reflectivity spectra has been calculated and compared with the available experimental data. (© 2007 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source] Influence of wurtzite,zinc-blende interfacial energy on growth and crystal phase of the III-V nanowiresPHYSICA STATUS SOLIDI (C) - CURRENT TOPICS IN SOLID STATE PHYSICS, Issue 2 2010Maxim Lubov Abstract Influence of wurtzite,zinc-blende energy on nucleation rate and growth kinetics is studied. The physical model of III-V nanowires growth is proposed. We show that wurtzite,zinc-blende interfacial energy caused formation of the zinc-blende structure on the initial stage of nanowires growth. Role of the fluctuations in quasi-periodic crystal structure formation representing alternating layers of wurtzite and zinc-blende phase is revealed. Calculations of the growth of the nanowire growth accounting fluctuations in the droplet alloy are carried out. The results of the calculations are in a good agreement with available experimental data. (© 2010 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source] | |||||||||||||