2008 Volume 77 Issue 11 Pages 114710
The dynamical mean field theory combined with exact diagonalization is used to study the valence instability in an extended periodic Anderson model. It is found that at fixed total electron number, the f-electron number is rapidly decreased against the f-electron level εf(0) in the presence of the repulsive interaction Ucf between a conduction electron and an f electron. This implies the enhancement of valence fluctuations due to Ucf. In addition, a first-order valence transition is likely to occur, provided the c–f mixing is small and Ucf is large enough to be comparable to the band width of conduction electrons. The quantum critical point of valence transition is identified in the εf(0)–Ucf plane. Implications for the valence fluctuations of the related Ce compounds are also discussed.
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