fix the conficit between mixing_restart and scf_os_stop (#5440)

Author: WHUweiqingzhou

source/module_elecstate/module_charge/charge_mixing.cpp

@@ -1708,11 +1708,6 @@ bool Charge_Mixing::if_scf_oscillate(const int iteration, const double drho, con
     ModuleBase::TITLE("Charge_Mixing", "if_scf_oscillate");
     ModuleBase::timer::tick("Charge_Mixing", "if_scf_oscillate");
 
-    if(threshold >= 0) // close the function
-    {
-        return false;
-    }
-
     if(this->_drho_history.size() == 0)
     {
         this->_drho_history.resize(PARAM.inp.scf_nmax);
@@ -1721,8 +1716,13 @@ bool Charge_Mixing::if_scf_oscillate(const int iteration, const double drho, con
     // add drho into history
     this->_drho_history[iteration - 1] = drho;
 
+    if(threshold >= 0) // close the function
+    {
+        return false;
+    }
+
     // check if the history is long enough
-    if(iteration < iternum_used)
+    if(iteration < iternum_used + this->mixing_restart_last)
     {
         return false;
     }

source/module_elecstate/module_charge/charge_mixing.h

@@ -102,8 +102,9 @@ class Charge_Mixing
     Base_Mixing::Mixing* get_mixing() const {return mixing;}
 
     // for mixing restart
-    int mixing_restart_step = 0; //which step to restart mixing during SCF
+    int mixing_restart_step = 0; //which step to restart mixing during SCF, always equal to scf_namx except for the mixing restart
     int mixing_restart_count = 0; // the number of restart mixing during SCF. Do not set mixing_restart_count as bool since I want to keep some flexibility in the future
+    int mixing_restart_last = 0; // the label of mixing restart step, store the step number of the last mixing restart
 
     // to calculate the slope of drho curve during SCF, which is used to determine if SCF oscillate
     bool if_scf_oscillate(const int iteration, const double drho, const int iternum_used, const double threshold);

source/module_esolver/esolver_ks.cpp

@@ -681,6 +681,7 @@ void ESolver_KS<T, Device>::iter_finish(const int istep, int& iter)
     // notice for restart
     if (PARAM.inp.mixing_restart > 0 && iter == this->p_chgmix->mixing_restart_step - 1 && iter != PARAM.inp.scf_nmax)
     {
+        this->p_chgmix->mixing_restart_last = iter;
         std::cout << " SCF restart after this step!" << std::endl;
     }
 }