CH_4、H_2O在CaCO_3(010)表面吸附的第一性原理研究

First-principles calculation of adsorption for methane and water on CaCO_3 (010) surface

基于密度泛函理论第一性原理方法,研究了CH_4和H_2O在CaCO_3(010)面上各高对称位的吸附情况,优化了CH_4与H_2O在T位、 B位和H位的吸附模型结构,计算了其在各高对称位的吸附能,并对其各自最稳定的吸附位吸附前后的物理结构和电子态密度进行了对比分析.结果表明:CH_4、 H_2O分子分别在LBⅢ位、 SBⅢ位最稳定,吸附能分别为-0.405 eV、-0.138 eV,是一种物理吸附,吸附前后键长键角的变化较小,表现为亲气;吸附后CH_4和H_2O的态密度曲线整体向低能量区偏移约7.5 eV、 5eV,吸附后CH_4和H_2O结构都更加稳定,吸附作用对CH_4和H_2O分子的电子结构影响显著.

Using the first principle calculation method of density functional theory,we studied the high symmetry adsorptions of methane and water on CaCO3(010)surface,optimized the adsorption model structures of methane and water in T,B and H sites,and calculated the high symmetry adsorption energies.The physical structures and electronic densities of states before and after adsorption are also compared and analyzed.The results show that the methane and water molecules have the most stable adsorption at LBⅢ site and SBⅢ site,and their adsorption energies are-0.405 eV and-0.138 eV,respectively.The absorption is a physical adsorption,and the bond length and bond angle change little before and after adsorption,behaving as atmophile.After adsorption,the density curves of methane and water shift to the low energy region about 7.5 eV and 5eV,respectively,and the structures of methane and water are more stable after adsorption.So the effects of adsorption on the electronic structures of methane and water molecules are remarkable.