9801751 Schlottmann This is a grant for theoretical research on strongly correlated electron systems. The award is funded by the Materials Theory Program in the Division of Materials Research and by the Office of Multidisciplinary Activities in the Mathematical and Physical Sciences Directorate. The NSF grant is coordinated with a similar one at DOE. Properties of highly correlated electrons, in particular, heavy fermion systems, mixed valent maganite compounds, Kondo insulators and one-dimensional conductors are studied theoretically. In heavy fermions the main focus is on the simultaneous treatment of Kondo screening and intersite interactions, effects of correlations among the itinerant electrons on the heavy electrons and the faint antiferromagneticallly ordered magnetic moments observed in some heavy-fermion compounds. The quadrupolar (Jahn-Teller) response of mixed valent manganese ions is studied within the framework of manganese impurity models and a pair of manganese ions. The origin of bound-states in the gap of Kondo insulators and the difference of spin and charge gaps are investigated. Methods employed are the Bethe Ansatz, the Quantum Inverse Scattering Method, and slave boson approaches. %%% This is a grant for theoretical research on strongly correlated electron systems. The award is funded by the Materials Theory Program in the Division of Materials Research and by the Office of Multidisciplinary Activities in the Mathematical and Physical Sciences Directorate. The NSF grant is coordinated with a similar one at DOE. A number of theoretical approaches will be taken to study strongly correlated electron systems. These systems include the so-called heavy fermion systems, mixed valent maganite compounds, Kondo insulators and one-dimensional conductors. Both the systems to be studied and the techniques to be used are at the forefront of modern condensed matter physics. ***
