Most of the research in my group involves trying to understand why reactions happen the way they do in different environments. Why do some reactions have low activation barriers in the gas phase while other similar reactions have large activation energies? How do surfaces change the interactions between reactants in catalysis? What happens to chemical pathways as high energy plasmas are incorporated? All of these questions are important ones that can be investigated using a combination of theoretical and experimental techniques.
The researchers in my group are shown here: Nianliu Zhang, Hong Zhao, Jennifer Wilcox, Paul Blowers, and Xiaobo Zheng (from left to right).
There are four major research thrusts in our research group. All of these projects rely heavily on quantum mechanical calculations and statistical mechanics as the primary tools of investigation. The first project is a theoretical investigation of beta-scission and depolymerization reactions. These reactions are important in environments as diverse as high temperature hydrocarbon cracking reactions to packaging material degradation over long time spans.
The second research thrust involves the experimental and theoretical study of mercury species that have been liberated through coal combustion. At the present time, the mechanisms that lead to the final mercury fate are poorly understood. Using high level quantum mechanical calculations partnered with novel mass spectroscopy techniques will allow us to understand the mercury interactions better. This work is funded by the Environmental Protection Agency.
The third research thrust concerns the mechanisms governing the electrochemical destruction of chlorinated hydrocarbons. The use of some metals over others leads to much better electrode performance in these environmentally related waste treatment processes. So far, though, research has not been able to lead to any predictive methods for determining a priori which metal will do well for converting the chlorinated wastes into more benign products. Experimental spinning electrode experiments are being coupled with ab initio quantum mechanical calculations in order to understand how better control and design of waste destruction can be accomplished. This work is funded by the National Science Foundation.
The final research thrust in our group involves the systematic exploration of various forms of transition state theory for estimating rate constants. The importance of highly accurate activation energies, reaction species geometries, and the use of appropriate approximations within the transition state formalism all affect the accuracy of the final rate constant estimations.
An Example of using QM calculations:
Quantum mechanical ab initio calculations can be used to look at reaction behavior under different conditions. Once some preliminary calculations have been done to find a reaction's transition state, another calculation, called the intrinsic reaction coordinate (IRC) calculation, can be done to determine if the transition state is linking the correct products with the correct products. One can then make a movie of the reaction to show how the reactants are microscopically rearranging to products. Several of the reaction pathways I have studied are shown below. Just click on the reaction name to see the movie.
H + HF -> H2
+ F
H + H2 -> H2
+ H
H + CH3CH2CH3
-> H2
+ CH2CH2CH3
H + CH3CH2NH2
-> H2
+ CH2CH2NH2
H + NH3 -> H2 +
NH2
H + CH4 -> H2
+ CH3
H + CH3OH -> H2 +
CH2OH
H + H2O -> H2
+ OH
H + CH3CH2OH
-> H2
+ CH2CH2OH
H + O2 -> OH + O
CH3 + CH4
->
CH4 + CH3
O + CH4 -> OH + CH3
O + NH3 -> OH + NH2
OH + CH4 -> H2O
+ CH3
OH + CH3 -> H2O
+ CH2
OH + CH2 -> H2O
+ CH
