Calculation Of Solid Surface And Adsorption Based On Density Functional Theory

The adsorption of small molecules on solid surfaces is a key part of the study of catalytic reactions and surface diffusion.After years of development,density functional theory(DFT),its prediction of the first principles of matter is gradually moving towards reality.It has become an indispensable and important method for studying surface adsorption;combined with cutting-edge in-situ characterization technology,the mechanism behind many phenomena has been revealed,greatly expanding the boundaries of human knowledge.In this paper,the DFT method is used to conduct research on two different systems in order to explore the microscopic mechanism behind the experimental phenomenon.For the Ziegler-Natta catalyst for olefin polymerization,different surface structures of the carrier MgCl2 were optimized(?-MgCl2:104,101,102,110;?-MgCl2:010,011,012,110,111),and the surface properties were explored;The adsorption behavior of TiCl4 and electron donors on different surface structures of MgCl2,and the co-adsorption of the two,the synergy,reconstruction and bonding characteristics of different adsorption structures were analyzed.Concluded as follow:1.There are more exposed sites on the four-coordinate MgCl2 surface,and the surface reconstruction effect is obvious,so the surface energy of four-coordinate MgCl2 surface is generally higher than the five-coordinate MgCl2 surface.2.The co-adsorption of TiC14 and internal electron donors(IDs)shows that the synergistic and electronic effects play an important role in the stabilization or destabilization of the co-adsorbed state.The increase and decrease of co-adsorption energy of IDs are related to attractive interaction and repulsive interaction,respectively.In some cases,due to strong repulsion,TiCl4 will desorb from the surface.The binding of IDs to the surface of MgCl2 is formed by the coordination bond provided by the HOMO of EB and the vacancies of Mg.Aiming at the different thermoelectric effects of different ionic liquids on the gold surface,the interaction of Au(111)surface with methanol and water molecules was studied,and two ionic liquids were explored([EMIm][Ac]and[EMIm][TFSI])The adsorption behavior on the Au(111)surface explores the interaction mechanism between the ionic liquid and the gold surface in terms of binding energy and electronic properties.Concluded as follow:1.Methanol and water molecules adsorbed on the surface of Au(111)have a strong electron density charge accumulation,which is combined with Au atoms through oxygen atoms.2.When the coverage is 2/3 ML,the water molecules are arranged in a hexagon on the surface of Au(111).Hydrogen bonds can be formed between adjacent water molecules to form a stable six-membered ring structure.When there are two layers of water molecules,the two layers of water molecules will form an interlocking double ice structure.3.By calculating the Gibbs free energy,the effect of temperature on the adsorption of ionic liquid is explored,thereby verifying the opposite thermoelectric phenomenon of[EMIm][Ac]and[EMIm][TFSI]on the Au(111)surface...