First-principles Calculations Of Rutile TiO₂?110? Surface Properties Coupled With Adsorption

In this paper,by using first-principles calculation method,we systematically stud-ied the surface properties of molecular or cluster adsorbed rutile Ti02(110).The mo-tivation lies in the fact that TiO2 is,not only an abundant and clean material for real world photocatalytic and photovoltaic applications,but also an ideal model for basic scientific study of surface photocatalytic processes and surface reactions.Although scientific investigations on titanium oxide have lasted for nearly half century,there are still important basic questions waiting to be answered.Such as the electron-phonon coupling,carriers' separation and carrier's relaxation pathways.To study the intrinsic properties of a system,sometimes we should impose external perturbation,then we can analyze the response and derive the intrinsic properties.In this dissertation,by investi-gating various adsorption system we studied the properties of rutile TiO2(110)surface.In chapter one,we briefly introduced the modern calculation methods for electronic structures.Starting from Hartree-Fock theory then to the versatile density functional theory(DFT)for condensed mater systems,we went through the main frame of those theories and the main approximation methods adopted.Besides,we also talked about the critical technique of basis and functional selecting.In the end of the chapter,we shed light on the time-dependent density functional theory to bring out the non-adiabatic molecular dynamics in the following chapter.In chapter two,we presented the first-principles molecular dynamics method.In the beginning we introduced several basic conceptions and common approximations in many-body theory.Then we focused on Ehrenfest mean field approximation and sur-face hopping method.After that,we showed the flowchart of non-adiabatic molecular dynamics based on Tully's fewest switches surface hopping method.In chapter three,we reported our investigation of electron-phonon coupling related properties in rutile TiO2 sysytem through formaldehyde adsorption,to name a few,po-laron's distribution,migration and carriers,relaxation.At first we systematically stud-ied the adsorption behavior of formaldehyde on rutile TiO2(110)surface.By trying different methods and taking related factors into consideration,we push forward the description of formaldehyde on TiO2 surfaces using density functional theory.Before our work,there's a long-standing debate over the most stable adsorption configuration of formaldehyde on TiO2 surf-aces between theoretical calculations and experimental observations.By using GGA+U and psedo-hydrogen saturation method,we obtained a better description of the distribution of excess electrons on rutile TiO2 surface.Then we get the physical picture of formaldehyde on rutile TiO2(110)surface which is consistent with latest experimental results.After that,we investigated the distribution of polaron under the influence of formaldehyde adsorption.By further taking thermal effect into consideration,we ran first-principles molecular dynamics to investigate the pathways of polaron migrating to surface.Besides,the adsorption of formaldehyde brought rich electronic structure in the gap.Different adsorption configurations at various adsorp-tion sites could contribute massive migration channels for carriers's migration.At last we investigated hole relaxation after formaldehyde adsorption by using non-adiabatic molecular dynamics method.In the forth chapter we reported the influence of molecular adsorption on excita-tion spectrum of rutile Ti02(110)surface.By varying adsorption sites,coverage and adsorbates,we found the key factors determining the strength of d-d transition.The we brought two proposals to test our model and we conformed them at the end from theoretical calculations.In the last chapter we reported the influence on electronic structure from silver cluster adsorbing on rutile TiO2 surface.We found a special interfacial state which could be utilized as the initial states for surface plasmon oscillation to improve the efficiency of surface catalytic reactions.