After the electron transfers from the metal electrode to the Fe3+(H2O)(6) ion, the free energy of activation of this electron transfer reaction is calculated, then using the transition probability which is calculated ...After the electron transfers from the metal electrode to the Fe3+(H2O)(6) ion, the free energy of activation of this electron transfer reaction is calculated, then using the transition probability which is calculated by the perturbed degeneration theory and the Fermi golden rule,, the rate constant is gotten. Compared with the experimental results, it is satisfactory.展开更多
Basing on the DFT calculations we propose the new theoretical model which describes both the surface tension σ of the short chain n-alkanes at their normal boiling points and their reaction rate constants with hydrox...Basing on the DFT calculations we propose the new theoretical model which describes both the surface tension σ of the short chain n-alkanes at their normal boiling points and their reaction rate constants with hydroxyl radicals OH<span style="white-space:nowrap;">•</span> (at 297 ± 2 K) on the basis of their molecular orbital electronic characteristics. It has been shown that intermolecular dispersion attraction within the surface liquid monolayer of these compounds, as well as their reaction rate constants k with OH<span style="white-space:nowrap;">•</span> radicals are determined by the energies <em>E<sub>orb</sub></em> of the specific occupied molecular orbitals which are the same in the determination of both the above physico-chemical characteristics of the studied n-alkanes. The received regression equations confirm the theoretically found dependences between the quantities of σ and k and the module |<em>E<sub>orb</sub></em>|. For the compounds under study this fact indicates the key role of their electronic structure particularities in determination of both the physical (surface tension) and the chemical (reaction rate constants) properties.展开更多
The new theoretical models describe both the solubility S of the shot chain n-alkanes in water at 298.15 K, and their reaction rate constants k with nitronium cation NO<sub>2</sub><sup>+ </sup>...The new theoretical models describe both the solubility S of the shot chain n-alkanes in water at 298.15 K, and their reaction rate constants k with nitronium cation NO<sub>2</sub><sup>+ </sup>at 293.15 K on the basis of their molecular orbital characteristics. It is shown that both the quantities S and k are determined by the energies E<sub>orb</sub> of the specific virtual (for S) and occupied (for k) molecular orbitals of these n-alkanes. The obtained regression equations confirm the theoretically found dependences of S and k on the absolute value of E<sub>orb</sub>. This fact demonstrates that the electronic structure particularities of the studied n-alkanes play a crucial role in both their above-mentioned physicochemical properties.展开更多
Microcanonical rate constants k(E) and canonical rate constants k(T) for unimolecular reactions have been obtained through the calculations of cumulative reaction probabilities N(E) with the unsymmetrical Eckart poten...Microcanonical rate constants k(E) and canonical rate constants k(T) for unimolecular reactions have been obtained through the calculations of cumulative reaction probabilities N(E) with the unsymmetrical Eckart potential tunneling correction. By way of example, the reactions HCN→CNH (I) and FNC→NCF (II) have been employed. For reaction (I), the calculated rate constants are in agreement with the experimental data; for reaction (II), the results are in accordance with the rate constants kCVT/MEPSAG(T) calculated by the common program POLYRATE.展开更多
The reaction of disilane with atomic hydrogen has been studied. This reaction involves both substitution and abstraction. Calculations show that the hydrogen abstraction is the strongest competing channel. The canonic...The reaction of disilane with atomic hydrogen has been studied. This reaction involves both substitution and abstraction. Calculations show that the hydrogen abstraction is the strongest competing channel. The canonical variational transition state theory with a small curvature tunneling correction (SCT) has been used for the kinetic calculation. The theoretical results are in good agreement with the available experimental data. Comparing the reactions of atomic hydrogen with disilane and silane, it can be seen that the reactivity of the Si-H bond is higher in Si2H6than that in SiH4.展开更多
The influence of a single water molecule on the reaction mechanism and kinetics of hydrogen abstraction from methanol （CH3OH） by the CIO radical has been investigated using ab initio calculations. The reaction proce...The influence of a single water molecule on the reaction mechanism and kinetics of hydrogen abstraction from methanol （CH3OH） by the CIO radical has been investigated using ab initio calculations. The reaction proceeds through two channels： abstraction of the hydroxyl H-atom and methyl H-atom of CH30H by CIO, leading to the formation of CH30 ＋ HOC1 （＋H20） and CH20H ＋ HOC1 （＋ H20）, respectively. In both cases, pre- and post-reactive complexes were located at the entrance and exit channel on the potential energy surfaces. Results indicate that the formation of CH2OH ＋ HOC1 （＋H20） is predominant over the formation of CH30 ＋ HOC1 （＋H20）, with ambient rate constants of 3.07 x 10^-19 and 3.01 x 10^-23 cm^3/（molecule.sec）, respectively, for the reaction without water. Over the temperature range 216.7-298.2 K, the presence of water is seen to effectively lower the rate constants for the most favorable pathways by 4-6 orders of magnitude in both cases. It is therefore concluded that water plays an inhibitive role on the CH30H ＋ ClO reaction under tropospheric conditions.展开更多
文摘After the electron transfers from the metal electrode to the Fe3+(H2O)(6) ion, the free energy of activation of this electron transfer reaction is calculated, then using the transition probability which is calculated by the perturbed degeneration theory and the Fermi golden rule,, the rate constant is gotten. Compared with the experimental results, it is satisfactory.
文摘Basing on the DFT calculations we propose the new theoretical model which describes both the surface tension σ of the short chain n-alkanes at their normal boiling points and their reaction rate constants with hydroxyl radicals OH<span style="white-space:nowrap;">•</span> (at 297 ± 2 K) on the basis of their molecular orbital electronic characteristics. It has been shown that intermolecular dispersion attraction within the surface liquid monolayer of these compounds, as well as their reaction rate constants k with OH<span style="white-space:nowrap;">•</span> radicals are determined by the energies <em>E<sub>orb</sub></em> of the specific occupied molecular orbitals which are the same in the determination of both the above physico-chemical characteristics of the studied n-alkanes. The received regression equations confirm the theoretically found dependences between the quantities of σ and k and the module |<em>E<sub>orb</sub></em>|. For the compounds under study this fact indicates the key role of their electronic structure particularities in determination of both the physical (surface tension) and the chemical (reaction rate constants) properties.
文摘The new theoretical models describe both the solubility S of the shot chain n-alkanes in water at 298.15 K, and their reaction rate constants k with nitronium cation NO<sub>2</sub><sup>+ </sup>at 293.15 K on the basis of their molecular orbital characteristics. It is shown that both the quantities S and k are determined by the energies E<sub>orb</sub> of the specific virtual (for S) and occupied (for k) molecular orbitals of these n-alkanes. The obtained regression equations confirm the theoretically found dependences of S and k on the absolute value of E<sub>orb</sub>. This fact demonstrates that the electronic structure particularities of the studied n-alkanes play a crucial role in both their above-mentioned physicochemical properties.
基金Project supported by the National Natural Science Foundation of China
文摘Microcanonical rate constants k(E) and canonical rate constants k(T) for unimolecular reactions have been obtained through the calculations of cumulative reaction probabilities N(E) with the unsymmetrical Eckart potential tunneling correction. By way of example, the reactions HCN→CNH (I) and FNC→NCF (II) have been employed. For reaction (I), the calculated rate constants are in agreement with the experimental data; for reaction (II), the results are in accordance with the rate constants kCVT/MEPSAG(T) calculated by the common program POLYRATE.
基金This work was supported by the National Natural Science Foundation of China （No.10865003） and the Guizhou University for Nationalities （2010）. The authors thank professors W. T. Duncan, R. L. Bell, and T. N. Truong or providing the rate program through the internet.
基金supported by the Major Research Plan of the National Natural Science Foundation of China(91441132)Fundamental Research Funds for the Central Universities,China(3132016127,3132016326,3132016019)~~
基金supported by the Major Research Plan of the National Natural Science Foundation of China(91441132)Fundamental Research Funds for the Central Universities,China(3132016127,3132016326)~~
文摘使用MP2/6-311++G(2d,2p)方法和基组,计算了丁酸甲酯单分子解离反应体系详细的势能面。应用RRKM理论,计算了在1000-5000 K的温度范围内的正则系综的速率常数。与此同时,在微正则系综下,我们计算了温度为1000-5000 K对应的能量从451.92到1519.52 k J?mol^(-1)的速率常数。计算结果表明反应通道2、4和5的非谐振效应比较明显。因此对于丁酸甲酯单分子解离反应体系来说其非谐振效应是不能忽视的。
基金the Research Fund for the Doctoral Program of High Education of China (Grant No. 1999042201).
文摘The reaction of disilane with atomic hydrogen has been studied. This reaction involves both substitution and abstraction. Calculations show that the hydrogen abstraction is the strongest competing channel. The canonical variational transition state theory with a small curvature tunneling correction (SCT) has been used for the kinetic calculation. The theoretical results are in good agreement with the available experimental data. Comparing the reactions of atomic hydrogen with disilane and silane, it can be seen that the reactivity of the Si-H bond is higher in Si2H6than that in SiH4.
基金supported by the National Natural Science Foundation of China (nos. 21577080, 91644214, 21707080)the Shandong Natural Science Fund for Distinguished Young Scholars (JQ201705)+1 种基金the Postdoctoral Science Foundation of China (no. 11440077311071)High Performance Computing Center of Shandong University
文摘The influence of a single water molecule on the reaction mechanism and kinetics of hydrogen abstraction from methanol （CH3OH） by the CIO radical has been investigated using ab initio calculations. The reaction proceeds through two channels： abstraction of the hydroxyl H-atom and methyl H-atom of CH30H by CIO, leading to the formation of CH30 ＋ HOC1 （＋H20） and CH20H ＋ HOC1 （＋ H20）, respectively. In both cases, pre- and post-reactive complexes were located at the entrance and exit channel on the potential energy surfaces. Results indicate that the formation of CH2OH ＋ HOC1 （＋H20） is predominant over the formation of CH30 ＋ HOC1 （＋H20）, with ambient rate constants of 3.07 x 10^-19 and 3.01 x 10^-23 cm^3/（molecule.sec）, respectively, for the reaction without water. Over the temperature range 216.7-298.2 K, the presence of water is seen to effectively lower the rate constants for the most favorable pathways by 4-6 orders of magnitude in both cases. It is therefore concluded that water plays an inhibitive role on the CH30H ＋ ClO reaction under tropospheric conditions.
