A New Approach of Accurate Reaction Rate Calculations Based on the First Principle

Feb. 21, 2005

Recently, Dr. Tao Wu, a young faculty member of Zhejiang University, put forward a systematic approach, according to the first principles of physics, by which reaction rate constants are able to be predicted theoretically based on atomic characters. His paper, entitled First-Principle Theory for the H + CH4 - H2 + CH3 Reaction, was published on the Magazine SCIENCE, on December 24, 2004.

A basic question of modern chemistry is that the rate of reactions can be calculated and predicted according to the fundamental nature of atoms and molecules. Traditionally, the calculation of rate constants fits only some smaller system of reactions (involving 2 to 4 atoms and 3 to 6 DOF), which restricts a further understanding of reaction systems with stronger effect of quantum, and which has larger errors between calculations and experiments. Based on Wu’s new method, a first-principle potential surface of multi-DOF can be automatically constructed to calculate the rate of reactions based on quantum dynamics theory, which is more practical, fits larger systems, and has greater accuracy. As a case study, all-dimensional rate constants of the reaction system of CH3 and H2, which is a primary reaction in Atmosphere Chemistry, Combustion Chemistry, and Catalyst, were most precisely calculated complying with quantum dynamics, and the corresponding result precision is not lower than that of experiments. At present, as an important breakthrough in theoretical chemistry, it is the largest system of rate constant calculation based on the first principle.

Dr. Wu has been working on micro-kinetics for many years, said Prof. Qi Wang, the director of the Institute of Molecular Design and Molecular Thermodynamics, Zhejiang University. In August 2003, Dr. Wu started his work in the Institute, and has mainly engaged in Micro-Kinetics, Molecular Simulation and Calculation Quantum Chemistry since then. The research project was started in 2001, when Dr. Wu was teaching in Technical University of Munich (TUM), Germany, where the project got subsidized by the University. After his return to China, he completed the research task with Prof. Manthe from TUM and Bielefeld University.

At present, using the method by Wu and the others, some researchers are applying the achievements on First-Principle Reaction Kinetics, into other fields of sciences and engineering, such as cytochemistry dynamics, with the help of approximate treatments. The systems have very strong quantum effects, featuring different behaviors from traditional dynamic theories, and therefore are difficult to be predicted by means of the traditional methods. However, further studies will be facilitated by Dr. Wu’s method.