Chemical-potentials-control.md

@@ -15,4 +15,20 @@ Chemical potentials are adjusted according to rule:
 ```
 
 # Fixed chemical potential mode
-TODO
\ No newline at end of file
+In order to execute calculations for fixed chemical potential you need to set in *input* file:
+```bash
+muchange                0.0      # do not change chemical potential
+npartconveps            1.0e+9   # ignore checking of particle number convergence criteria
+```
+
+In addition, you need to set the value of chemical potentials. For this use `process_params` function in [problem-definition.h](https://gitlab.fizyka.pw.edu.pl/gabrielw/wslda/-/blob/public/st-project-template/problem-definition.h)
+```c
+void process_params(double *params, double *kF, double *mu, size_t extra_data_size, void *extra_data)
+{
+   // hard set of chemical potentials
+   mu[SPINA] = YOUR_VALUE; // <-- you can promote it as user-defined parameter
+   mu[SPINB] = YOUR_VALUE; // <-- you can promote it as user-defined parameter
+
+   // ...
+}
+```
\ No newline at end of file