calculate energy in the beginning only once

src/SPIN/min_spin.cpp

@@ -133,7 +133,7 @@ int MinSpin::iterate(int maxiter)
     // optimize timestep accross processes / replicas
     // need a force calculation for timestep optimization
 
-    energy_force(0);
+    if (iter == 0) energy_force(0);
     dts = evaluate_dt();
 
     // apply damped precessional dynamics to the spins

src/SPIN/min_spin_oso_cg.cpp

@@ -180,8 +180,8 @@ int MinSpinOSO_CG::iterate(int maxiter)
   
     // optimize timestep accross processes / replicas
     // need a force calculation for timestep optimization
-  
-    energy_force(0);
+
+    if (iter == 0) energy_force(0);
     dts = evaluate_dt();
   
     calc_gradient(dts);

src/SPIN/min_spin_oso_lbfgs.cpp

@@ -190,7 +190,7 @@ int MinSpinOSO_LBFGS::iterate(int maxiter)
     // optimize timestep accross processes / replicas
     // need a force calculation for timestep optimization
   
-    energy_force(0);
+    if (iter == 0) energy_force(0);
     //  dts = evaluate_dt();
     //  dts = 1.0;
     calc_gradient(1.0);