Research Abstracts Online
January 2010 - March 2011
University of Minnesota Twin Cities
College of Science and Engineering
of Chemical Engineering and Materials Science
PI: Matteo Cococcioni, Associate Fellow
Computational Study of Transition Metal Compounds and Catalytic Systems
These researchers are involved in several projects. The first involves transition metal-based minerals and superconductors. New DFT-based corrective functionals are being defined and tested to study the behavior of Fe-bearing minerals of the earth’s interior and the Cu-based parent materials of high-Tc superconductors. In representative systems of both classes (FeO and CuO), calculations are revealing very interesting effects on the structural stability, related to orbital ordering. Further investigations based on the calculation of the electron-phonon coupling will help to better explain their behavior.
Another project involves structural transition in magnetic shape-memory alloys. This research activity focuses on the prototype magnetic shape memory alloy Ni2MnGa and aims to identify the electronic mechanisms controlling magnetic and structural transformations. Calculations in progress are highlighting interesting effects of electronic correlations on the structural stability of the austenite phase and its magnetization. The analysis will be extended to the martensite structure to precisely assess the interdependence of structural and magnetic degrees of freedom and tune their coupling to optimal levels.
The researchers are also studying catalytic reactions on zeolite-supported active centers. One project explores the possibility to synthesize liquid fuel molecules from under-utilized and abundant C1 feedstocks (such as syn-gas or methanol) through C-C bond formation reactions catalyzed on the Bronsted acids of various zeolites. Different systems are being preliminarily screened as possible supports and the reactivity of selected active centers is being computed for some of them. Zeolites are also being investigated as supports for metal active centers in the adsorptive desulfurization of fuels. Several metallic species are being screened to identify an optimal candidate able to selectively adsorb H2S without being poisoned by other contaminants.
A final project involves the study of electronic levels of phosphorescent sensitizers for organic solar cells. An Ir terpyridine - Ir(ppy)3-complex is being investigated as a phosphorescent sensitizer of organic solar cells. Recently developed corrective energy functionals are providing precious insight on the behavior of this compound and yield electronic energy levels in agreement with experiments. Possible chemical modifications of this compound will be explored to maximize its efficiency and compatibility with current cells.
Andrea Floris, Collaborator
Burak Himmetoglu, Graduate Student
Vamshi Mohan Katukuri, Graduate Student
Alex Marchenko, Undergraduate Student
Mark N. Mazar, Graduate Student
Chun-Yi Sung, Research Associate