混合式格点法研究氧在银或银合金表面的吸附动力学

本文改进了混合式格点法对第一时间步的计算方法, 在保持原有精度的基础上, 减少计算时间约三个数量级。用这一方法, 研究了氧在银及其合金表面的吸附动力学。计算表明: 氧分子在银表面有效吸附的反应阈值是6.29kJ/mol, 这和实验所得的活化能相同。当氧分子动量大于45a.u.或合金中金配比大于0.30时,氧分子均无法在银及其合金表面形成稳定吸附, 这此结果和实验一致。计算中没有发现分子氧直接解离成原子氧的现象。从计算结果中推测, 处在振动激发态的氧分子比处在振动基态的氧分子更容易吸附在银表面。

A mixed type grid method study on the dynamics of oxygen adsorption on silver of silver alloy surface

The dynamics of oxygen adsorption on silver or silver alloy surface has been studied with a mixed typegrid method. The method modifies the first step calculation procedure of the ususl mixed type grid method, reducing the cpu time for about 3 orders of magnititude and keeping the original calculation precision unchanged. Theresults of calculation show that the threshold value of adsorption, corresponding roughly to the experimental activation energy, is 6.29kJ/mol, and the steady oxygen adsorption does not present when the momentum of oxygen is more than 45a.u. or when the proportion of gold in Ag-Au alloy is more than 0.30. These results are in agreement with experiments. The calculation result shows no oxygen atom resulting from O~2 direct dissociation, this supports the complex multi-step reaction mechanism of oxygen adsorption on silver surface proposed by Charles. The calculation result also shows that adsorption of oxygen on silver is easier for a vibration excited oxygen molecule than for a ground state one.