The surface disproportionation reaction mechanism of aluminum subchloride on the aluminum （100） surfaces has been investigated by the plane-wave density functional theory （DFT）. Three kinds of possible reaction me...The surface disproportionation reaction mechanism of aluminum subchloride on the aluminum （100） surfaces has been investigated by the plane-wave density functional theory （DFT）. Three kinds of possible reaction mechanism of AlCl disproportionation reaction on the aluminum （100） surfaces have been taken into account. The structures of reactants and products have been optimized, transition states have been confirmed and activation energies have been calculated. The adsorption energy of reactants and desorption energy of products have been determined. All of these have been employed to confirm the reaction mechanism and the rate determining step ofAlCl disproportionation reaction on the aluminum （100） surfaces.展开更多
The mechanism and dynamical properties for the reaction of HCCO radicals with NO were investigated theoretically. The minimum energy paths(MEP) of the reaction were calculated by using the density functional theory(DF...The mechanism and dynamical properties for the reaction of HCCO radicals with NO were investigated theoretically. The minimum energy paths(MEP) of the reaction were calculated by using the density functional theory(DFT) at the B3LYP/6-311+G ** level, and the energies along the MEP were further refined at the QCISD(T)/6-311+G ** level. It is found that the reaction mechanism of the title reaction involves three channels, producing HCNO+CO, HONC+CO and HCN+CO 2 products, respectively. Channel 1 is the most favorable path. The rate constant for channel 1 were calculated over a temperature range of 800—2500 K by using the canonical variational transition-state theory(CVT). The rate constant for the main path is negatively dependent on temperature, which is a characteristic of radical reactions with negative activation energy, and the variational effect for the rate constant calculation is small in the whole temperature range.展开更多
The reaction mechanism of SiCl4 with H2 has been studied theoretically using Gaussian 98 program at B3LYP/6-311G^＊ level. Three different reaction paths （a, b, c） in the gas phase were obtained. The geometries, vib...The reaction mechanism of SiCl4 with H2 has been studied theoretically using Gaussian 98 program at B3LYP/6-311G^＊ level. Three different reaction paths （a, b, c） in the gas phase were obtained. The geometries, vibrational frequencies and energies of every stagnation point in the reaction channel were calculated and the mechanisms have been confirmed. The results show that path a has an activation energy of 79.12 kcal/mol, which was considered as the main reaction path. Comparably, paths b and c have the energy barriers of 125.07 and 136.25 kcal/mol, respectively. The reaction rate constant was calculated by TST method over a wide temperature range of 900～1600 K, which further confirmed that path a was the main reaction channel展开更多
The mechanism of collision reaction among protons, N2 and water vapor was theoretically studied using Den-sity Functional Theory. The geometries of reactants, transition states, intermediates and products were optimiz...The mechanism of collision reaction among protons, N2 and water vapor was theoretically studied using Den-sity Functional Theory. The geometries of reactants, transition states, intermediates and products were optimized at the B3LYP/6-311+G** level by the BERNY gradient analysis method. Transition states and intermediates have been identified by vibrational frequency analysis. The relationship among reactants, intermediates, transition states and products was affirmed by IRC calculation. The variations of energy and geometry along the IRC-determined reaction paths were described. The possible reaction pathways were represented and the optimal one was decided from the viewpoint of energy.展开更多
The density functional theory（DFT） calculations were performed to investigate a typical Norrish/Yang type II photoreaction of 5-methylbicyclo[1.1.1]-pentanyl ketone.The results reveal the essential correlation betwe...The density functional theory（DFT） calculations were performed to investigate a typical Norrish/Yang type II photoreaction of 5-methylbicyclo[1.1.1]-pentanyl ketone.The results reveal the essential correlation between structures on the one hand and energies,on the other hand,of the reactants,transition states and products based on both singlet ground（S0） and triplet excited（T1） potential energy surfaces.The feasible mechanism indicates that an intramolecular Norrish/Yang cyclization reaction takes place via H-abstraction to obtain the sole chiral cyclobutanol photoproduct.The located crossing point plays an important role in the cyclization process,which permits intersystem crossing（ISC） from T1 to S0 state.The rate-determining step may be to experience ISC between two different potential energy surfaces,requiring sufficient time for electron spin reversion,i.e.,spin multiplicity alteration.These conclusions are further confirmed by the second-order M ller-Plesset perturbation theory（MP2） calculations.展开更多
The mechanism and dynamical properties for the reaction of NCS and OH radicals have been investigated theoretically. The minimum energy paths (MEP) of the reaction were calculated using the density functional theory (...The mechanism and dynamical properties for the reaction of NCS and OH radicals have been investigated theoretically. The minimum energy paths (MEP) of the reaction were calculated using the density functional theory (DFT) at the B3LYP/6-311+G** level, and the energies along the MEP were further refined at the QCISD(T)/6-311+G** level. As a result, the reaction mechanism of the title reaction involves three channels, producing HCS+NO and HNC+SO products, respectively. Path I and path II are competitive, with some advantages for path I in kinet-ics. As for path III, it looks difficult to react for its high energy barrier. Moreover, the rate constant have been cal-culated over the temperature range of 8002500 K using canonical variational transition-state theory (CVT). It was found that the rate constants for both path I and path II are negatively dependent on temperature, which is similar with the experimental results for reactions of NCS with NO and NO2, and the variational effect for the rate constant calculation plays an important role in whole temperature range.展开更多
基金Supported by the Joint Funds of the National Natural Science Foundation of China(No.u0837604) the Funds for Applied Basic Researches of Yunnan Province(No.2010CD022)
文摘The surface disproportionation reaction mechanism of aluminum subchloride on the aluminum （100） surfaces has been investigated by the plane-wave density functional theory （DFT）. Three kinds of possible reaction mechanism of AlCl disproportionation reaction on the aluminum （100） surfaces have been taken into account. The structures of reactants and products have been optimized, transition states have been confirmed and activation energies have been calculated. The adsorption energy of reactants and desorption energy of products have been determined. All of these have been employed to confirm the reaction mechanism and the rate determining step ofAlCl disproportionation reaction on the aluminum （100） surfaces.
文摘The mechanism and dynamical properties for the reaction of HCCO radicals with NO were investigated theoretically. The minimum energy paths(MEP) of the reaction were calculated by using the density functional theory(DFT) at the B3LYP/6-311+G ** level, and the energies along the MEP were further refined at the QCISD(T)/6-311+G ** level. It is found that the reaction mechanism of the title reaction involves three channels, producing HCNO+CO, HONC+CO and HCN+CO 2 products, respectively. Channel 1 is the most favorable path. The rate constant for channel 1 were calculated over a temperature range of 800—2500 K by using the canonical variational transition-state theory(CVT). The rate constant for the main path is negatively dependent on temperature, which is a characteristic of radical reactions with negative activation energy, and the variational effect for the rate constant calculation is small in the whole temperature range.
基金This work was supported by the Foundation of Education Committee of Liaoning Province (No.990321076)
文摘The reaction mechanism of SiCl4 with H2 has been studied theoretically using Gaussian 98 program at B3LYP/6-311G^＊ level. Three different reaction paths （a, b, c） in the gas phase were obtained. The geometries, vibrational frequencies and energies of every stagnation point in the reaction channel were calculated and the mechanisms have been confirmed. The results show that path a has an activation energy of 79.12 kcal/mol, which was considered as the main reaction path. Comparably, paths b and c have the energy barriers of 125.07 and 136.25 kcal/mol, respectively. The reaction rate constant was calculated by TST method over a wide temperature range of 900～1600 K, which further confirmed that path a was the main reaction channel
基金Project supported by Ministry of Education (the training project of elitist) Foundation (No. [2001]3) and the Young Teacher Fund of Northeast Nor-mal University (No. 111382).
文摘The mechanism of collision reaction among protons, N2 and water vapor was theoretically studied using Den-sity Functional Theory. The geometries of reactants, transition states, intermediates and products were optimized at the B3LYP/6-311+G** level by the BERNY gradient analysis method. Transition states and intermediates have been identified by vibrational frequency analysis. The relationship among reactants, intermediates, transition states and products was affirmed by IRC calculation. The variations of energy and geometry along the IRC-determined reaction paths were described. The possible reaction pathways were represented and the optimal one was decided from the viewpoint of energy.
基金Supported by the National Natural Science Foundation of China(No.20904007)
文摘The density functional theory（DFT） calculations were performed to investigate a typical Norrish/Yang type II photoreaction of 5-methylbicyclo[1.1.1]-pentanyl ketone.The results reveal the essential correlation between structures on the one hand and energies,on the other hand,of the reactants,transition states and products based on both singlet ground（S0） and triplet excited（T1） potential energy surfaces.The feasible mechanism indicates that an intramolecular Norrish/Yang cyclization reaction takes place via H-abstraction to obtain the sole chiral cyclobutanol photoproduct.The located crossing point plays an important role in the cyclization process,which permits intersystem crossing（ISC） from T1 to S0 state.The rate-determining step may be to experience ISC between two different potential energy surfaces,requiring sufficient time for electron spin reversion,i.e.,spin multiplicity alteration.These conclusions are further confirmed by the second-order M ller-Plesset perturbation theory（MP2） calculations.
基金Project supported by the Natural Science Foundation of Jilin Province (No. 20010344) the Foundation of Education Bureau of Hainan Province (No. hjkj200312) and the Science Foundation for Excellent Youth of Northeast Normal University (No. 111382).
文摘The mechanism and dynamical properties for the reaction of NCS and OH radicals have been investigated theoretically. The minimum energy paths (MEP) of the reaction were calculated using the density functional theory (DFT) at the B3LYP/6-311+G** level, and the energies along the MEP were further refined at the QCISD(T)/6-311+G** level. As a result, the reaction mechanism of the title reaction involves three channels, producing HCS+NO and HNC+SO products, respectively. Path I and path II are competitive, with some advantages for path I in kinet-ics. As for path III, it looks difficult to react for its high energy barrier. Moreover, the rate constant have been cal-culated over the temperature range of 8002500 K using canonical variational transition-state theory (CVT). It was found that the rate constants for both path I and path II are negatively dependent on temperature, which is similar with the experimental results for reactions of NCS with NO and NO2, and the variational effect for the rate constant calculation plays an important role in whole temperature range.
