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为了节省计算时间和资源,研究真实体系的表面吸附问题,少数科研工作者采用分子力学研究分子的表面吸附问题。但是我们知道分子力学方法采用了“Born-Oppenheimer”近似,忽略了电子的运动,只计算与原子核位置相关的体系能量,因此不能求解与电子运动和分布相关的问题。然而表面吸附可以划分为物理吸附和化学吸附两种情况。在物理吸附过程中,分子的电子运动和分布并没有发生变化。而在化学吸附过程中,分子的电子运动和分布发生了变化。那么用分子力学来研究表面吸附中的物理吸附过程忽略化学吸附,到底会对最终的吸附分析造成多大的误差呢?用分子力学来研究表面吸附究竟是否可行呢?为了消除这些困惑,我们通过分子力学优化计算得到了TiO_2(110)表面对无机分子(H_2O,CO_2),有机小分子(CH_3OH,CHOOH,CH_2O),共轭分子(Bi-isonicotinic acid)的分子吸附能,并将这些吸附能与实验,其他量化计算(DFT,PM3)的结果进行对比。我们的数据表明,用分子力学计算得到的吸附能与实验值,量化计算值都相当接近。因此用分子力学来研究表面吸附是可行的。
In order to save computational time and resources, to study the surface adsorption problem of real system, a few scientists use molecular mechanics to study the surface adsorption problem of molecules. However, we know that the molecular mechanics approach uses the "Born-Oppenheimer approximation, ignoring the movement of electrons and calculating only the energy of the system associated with the position of the nucleus, and therefore can not solve the problems associated with electron movement and distribution. However, the surface adsorption can be divided into physical adsorption and chemical adsorption of two cases. In the physical adsorption process, the molecular electron movement and distribution did not change. In the chemical adsorption process, the molecular electron movement and distribution have changed. So molecular mechanics to study the surface adsorption process of physical adsorption ignoring the chemical adsorption, in the end what the final analysis of adsorption caused by how much error? Using molecular mechanics to study the surface adsorption is feasible? In order to eliminate these confusion, we through molecules The molecular adsorption energies of TiO 2 (110) surface on inorganic molecules (H 2 O, CO 2), organic small molecules (CH 3 OH, CHOOH, CH 2 O) and conjugated molecules (Bi-isonicotinic acid) Experiments, other quantitative calculations (DFT, PM3) results were compared. Our data show that the adsorption energy calculated by molecular mechanics is quite close to the experimental values and the calculated values. Therefore, using molecular mechanics to study surface adsorption is feasible.