Convergence-control.md

@@ -38,3 +38,18 @@ E_pairext: NEW=               0 OLD=               0 DIFF=               0 CONVS
     E_tot: NEW=      0.42400609 OLD=      0.42400536 DIFF=   7.2864682e-07 CONVSTATUS=  PASS
 ```
 
+# Ajusting of chemical potentials
+Static codes adjust chemical potentials automatically in such way to provide a solution with requested particle number. Following parameters control adjusting process:
+```bash
+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:  
+```math
+\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}
+```