F hole screening

The upper band is qualitatively the same as the simple two-band model discussed in section 3.1.2, but the band mass at zero temperature is enhanced by roughly a factor of 5 for fi 0) = 13r], where /r(0) is the Fermi level as temperature T=0 (Liu 1987, 1988). This factor plus the correlation effect due to Uk could put the mass enhancement factor to within the measured range of 20-30. When there are many f levels and many broad bands as in a real LDA calculation, there should be a one-to-one correspondence between the model bands and the LDA bands at the Fermi level. On the other hand, until the f hole screening dynamics can be calculated from realistic band eigenvalues and eigenstates, the present theory should only be considered qualitative or at most semi-quantitative. The quantity /r(0) cannot be determined with certainty, and we will treat it as a parameter in the model calculation. 

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