团簇Mn_3BP动力学和热力学稳定性

Study on kinetics and thermodynamic stability of cluster Mn_3BP

基于密度泛函理论和拓扑学原理,在B3LYP/Lanl2dz赝势基组水平下对团簇Mn3BP的构型进行优化,得到优化构型9种。分别从化学动力学和热力学稳定性两个方面对9种优化构型进行稳定性研究分析。结果表明:构型1(4)是最终能够稳定存在的构型,且热力学稳定性最好的构型,各异构化反应均直接或间接向它们转化(除TS3(4)-2(4)外),构型3(4)和2(4)极难转化,容易共存。未发生异构化反应的构型4(4)和5(4)可稳定存在,构型3(2)的热力学稳定性差,但暂未发现其异构化反应构型。热力学稳定性是异构化反应限度决定性影响因素:团簇反应物与生成物的能量差值ΔE增大,异构化反应的平衡常数K也随之增大。在现有异构化反应的基础上提出ln K=0.40107ΔE+0.75673,用以预测团簇未发现的异构化反应的反应限度,即用ΔE来预测未知的K。

Based on density functional theory and topological principles,configurations of Mn_3BP were optimized at the B3LYP/Lanl2 dz potential group level,and nine optimized configurations were obtained. The stability of the nine optimized configurations was analyzed from two aspects such as chemical kinetics and thermodynamic stability. The results show that configuration 1（4）is the ultimate stable configuration having the best thermodynamic stability. Each isomerization reaction is directly or indirectly converted to them（except for TS3（4）-2（4））. Configurations 3（4）and 2（4）are extremely difficult to convert and thus easily coexist. Configurations 4（4）and 5（4）where isomerization do not occur are stable. Configuration 3（2）has a poor thermodynamic stability,but its isomerization reaction configuration has not yet been found. Thermodynamic stability plays a decisive role in affecting the isomerization reaction limit： as the energy difference ΔE between the reactants and the products of the cluster increases,the equilibrium constant K of the isomerization reaction also increases.Based on the existing isomerization reactions,correlation ln K=0.40 107ΔE＋0.75 673 is proposed that can be used to predict the limit of the isomerization reactions yet to be found in the cluster,that is,using the knownΔE to predict the unknown K.