Fix: add energy_stable_count to ensure energy threshold is really achieved

source/module_esolver/esolver_fp.h

@@ -66,6 +66,8 @@ namespace ModuleESolver
 
         bool conv_elec; // If electron density is converged in scf.
 
+        int energy_stable_count = 0; // Counter for stable energy convergence.
+
       protected:
         //! Something to do after SCF iterations when SCF is converged or comes to the max iter step.
         virtual void after_scf(const int istep);

source/module_esolver/esolver_ks.cpp

@@ -421,6 +421,7 @@ void ESolver_KS<T, Device>::runner(const int istep, UnitCell& ucell)
     bool firstscf = true;
     this->conv_elec = false;
     this->niter = this->maxniter;
+    this->energy_stable_count = 0;
 
     // 4) SCF iterations
     double diag_ethr = PARAM.inp.pw_diag_thr;
@@ -668,8 +669,18 @@ void ESolver_KS<T, Device>::iter_finish(int& iter)
     // add a energy threshold for SCF convergence
     if (this->conv_elec == 0) // only check when density is not converged
     {
-        this->conv_elec
-            = (iter != 1 && std::abs(this->pelec->f_en.etot_delta * ModuleBase::Ry_to_eV) < this->scf_ene_thr);
+        if (iter != 1 && std::abs(this->pelec->f_en.etot_delta * ModuleBase::Ry_to_eV) < this->scf_ene_thr)
+        {
+            this->energy_stable_count++;
+        }
+        else
+        {
+            this->energy_stable_count = 0;
+        }
+        if (this->energy_stable_count >= 2) // energy stable for 2 steps
+        {
+            this->conv_elec = true;
+        }
     }
 }