Chemical Reaction Dynamics of PeCB and TCDD Decomposition:A Tight-Binding Quantum Chemical Molecular Dynamics Study with First-Principles Parameterization

摘要

The decomposition reaction dynamics of 2,3,4,4',5-penta-chlorinated biphenyl(2,3,4,4',5-PeCB),3,3',4,4',5-penta-chlorinated biphenyl(3,3',4,4',5-PeCB),and 2,3,7,8-tetra-chlorinated dibenzo-p-dioxin(2,3,7,8-TCDD)was clarified for the first time at atomic and electronic levels,using our novel tight-binding quantum chemical molecular dynamics method with first-principles parameterization.The calculation speed of our new method is over 5000 times faster than that of the conventional first-principles molecular dynamics method.We confirmed that the structure,energy,and electronic states of the above molecules calculated by our new method are quantitatively consistent with those by first-principles calculations.After the confirmation of our methodology,we investigated the decomposition reaction dynamics of the above molecules and the calculated dynamic behaviors indicate that the oxidation of the 2,3,4,4',5-PeCB,3,3',4,4',5-PeCB,and 2,3,7,8-TCDD proceeds through an epoxide intermediate,which is in good agreement with the previous experimental reports and consistent with our static density functional theory calculations.These results proved that our new tight-binding quantum chemical molecular dynamics-method with first-principles parameterization is an effective tool to clarify the chemical reaction dynamics at reaction temperatures.