Collaborative Research Centre 546

"Structure, Dynamics and Reactivity of Aggregates of Transition Metal Oxides"

Project C6
 

General information
 

Abstract:

In this project we continue to study the geometric structure as well as electronic and vibrational properties of vanadium oxide surfaces using ab initio methods where also coordinatively unsaturated surfaces are to be included. Further, our studies will be extended to complex vanadium and oxygen containing compounds as, for example, different vanadium phosphates which are examined experimentally in project B2. Amongst other important subjects we want to learn about the relationship between local coordination and electronic parameters of the metal and oxygen atoms in the compound and on its surface. This requires studies on different V_xO_y and V_xP_yO_z systems including their differently oriented surfaces where electronic properties of the reconstructed surfaces are to be compared with those of the ideal bulk terminated surfaces. Further, our previous studies on oxygen vacancies at V_xO_y surfaces will be extended by calculations on the reaction of small molecules (e. g. CO, NO, small hydrocarbons) near vacancies including their oxidation by surface oxygen. Possible molecular candidates are chosen in close agreement with other project groups of the Sfb.
Our theoretical studies focus on ab initio density-functional theory (DFT) methods where electronic and vibrational properties of local environments in the bulk and at its surface are evaluated within the cluster approach. We have also developed new methods to calculate (angle-resolved) X-ray absorption spectra which we will apply to studies of electronic core excitation processes near oxygen centers of the different oxides. Our theoretical results, if compared with experimental NEXAFS spectra obtained in projects C1 and B2, will allow a detailed analysis of the excitations processes involved as well as a discrimination between differently coordinated oxygen in the substrates.

Publications