Development and application of a novel quantum-chemical molecular-dynamics method for degradation dynamics of organic lubricants under high temperatures and pressures

摘要

The dynamics of the degradation process of a monoester (ethyl acetate) at reaction temperatures was clarified for the first time by a novel tight-binding, quantum-chemical, molecular-dynamics method with initial parameters that are determined completely on the basis of first-principles calculations. It was confirmed that the proposed method can calculate the structure, electronic states and total energy of a monoester and its fragments as accurately as the density-functional calculations, while the CPU time of the new method is over 5000 times faster than that of the density-functional calculations. In the case of the acetic ester molecule, the β-hydrogen which is located at the ethanol group was cleaved quickly. Compared to it, α-hydrogen was cleaved more slowly than β-hydrogen. Each atom expressed cleavage and association with repetition. As a whole, degradation phenomena were observed in this simulation. This observation agrees with experimental data.