atztogo's diary

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Entropy of non-interacting electrons

$S=-gk_{\mathrm{B}}\Sigma_i[f_i \ln f_i + (1-f_i)\ln (1-f_i)]$

[tex: g]:degree of degeneracy
[tex: f_i]:probability that a state is occpied $f_i = \left[1+\exp\left(\frac{E-\mu}{T}\right)\right]^{-1}$