Chemical potentials control

Ajusting of chemical potentials

Static codes adjust chemical potentials automatically in such a way to provide a solution with requested particle number. Following parameters control adjusting process:

muchange                0.5      # coefficient for changing chemical potential, default=0.5
mumaxchange             0.05     # maximal allowed changed of chemical potential per iteration,
                                 # in units of Fermi energy

Chemical potentials are adjusted according to rule:

$$\begin{aligned} \Delta\mu_{\sigma}^{(i)} &= \textrm{muchange}\,\frac{N_{\sigma}^{(\textrm{req.})}-N_{\sigma}^{(i)}}{N_{\sigma}^{(\textrm{req.})}}\\\ \textrm{if}\,|\Delta\mu_{\sigma}^{(i)}/\varepsilon_F|&>\textrm{mumaxchange}:\,\textrm{decrease}\,\textrm{magnitude}\,\textrm{of}\,\Delta\mu_{\sigma}^{(i)}\\\ \mu_{\sigma}^{(i+1)} &= \mu_{\sigma}^{(i+1)} + \Delta\mu_{\sigma}^{(i)} \end{aligned}$$

Fixed chemical potential mode

TODO