Xu Yuqing, Wong Kin-Yiu, Wang Meishan
School of Physics and Optoelectronic Engineering, Ludong University, Yantai, 264025, China.
PO Box, 68233, Kowloon East Post Office, Hong Kong.
Chemphyschem. 2023 Mar 14;24(6):e202200571. doi: 10.1002/cphc.202200571. Epub 2022 Dec 12.
Kinetic isotope effect values on the decarboxylation of 3-carboxybenzisoxazole have been computed using the second-order Kleinert's variational perturbation theory in the framework of Feynman's path integrals along with the potential energy surface obtained at the MP2/6-31+G(d) level. Good agreement with the experimental data was obtained, demonstrating that this novel computational approach for computing KIE values of organic reaction is a viable alternative to the traditional method employing the Bigeleisen equation and harmonic vibrational frequencies. Compared with the experimental measurements, consideration of anharmonicity and tunneling effects can significantly improve the calculated KIE values, reducing the root-mean-square deviation from 1.19 % for traditional method to 0.20 % for path-integral method.
在费曼路径积分框架下，利用二阶克莱纳特变分微扰理论并结合在MP2/6 - 31 + G(d)水平获得的势能面，计算了3 - 羧基苯并异恶唑脱羧反应的动力学同位素效应值。计算结果与实验数据吻合良好，表明这种计算有机反应动力学同位素效应值的新计算方法是采用比格莱森方程和谐波振动频率的传统方法的可行替代方案。与实验测量值相比，考虑非谐性和隧穿效应可显著提高计算得到的动力学同位素效应值，将均方根偏差从传统方法的1.19%降低到路径积分方法的0.20%。
