bug fix for mc

Author: Weiwei Wang

examples/mc/skx.py

@@ -17,13 +17,12 @@ def run(mesh):
 
     mc = MonteCarlo(mesh, name='test1')
     mc.set_m(init_m)
-    mc.set_options(H=[0,0,2e-2], J=50.0, D=0.18*50, T=20.0)
-    mc.run(steps=200)
-
+    mc.set_options(H=[0,0,0.5], J=50.0, D=0.27*50, T=5.0)
+    mc.run(steps=200000, save_m_steps=None, save_vtk_steps=1000, save_data_steps=10)
 
 if __name__=='__main__':
 
     #mesh = CuboidMesh(nx=174,ny=150, nz=1, pbc='2d')
-    mesh = CuboidMesh(nx=50, ny=60, nz=1, periodicity = (True, True, False))
+    mesh = CuboidMesh(nx=100, ny=100, nz=1, periodicity = (True, True, False))
 
     run(mesh)

fidimag/atomistic/lib/mc.c

@@ -64,8 +64,8 @@ double compute_energy_difference(double *spin, double *new_spin, int *ngbs, doub
             energy1 -= J*dot(&spin[3*i], &spin[3*k]);
             energy1 += D*dmi_energy_site(&spin[3*i], &spin[3*k], j);
 
-            energy2 -= J*dot(&new_spin[3*i], &new_spin[3*k]);
-            energy2 += D*dmi_energy_site(&new_spin[3*i], &new_spin[3*k], j);
+            energy2 -= J*dot(&new_spin[3*i], &spin[3*k]);
+            energy2 += D*dmi_energy_site(&new_spin[3*i], &spin[3*k], j);
 
         }
     }

fidimag/atomistic/mc.py

@@ -33,6 +33,7 @@ def __init__(self, mesh, name='unnamed'):
         self.vtk = SaveVTK(self.mesh, name=name)
 
         self.step = 0
+        self.skx_num = 0
         self.set_options()
 
     def set_options(self, J=50.0, D=0, H=None, seed=100, T=10.0):
@@ -104,6 +105,7 @@ def skyrmion_number(self):
         nz = self.mesh.nz
         number = clib.compute_skyrmion_number(
             self.spin, self._skx_number, nx, ny, nz, self.mesh.neighbours)
+        self.skx_num = number
         return number
 
 
@@ -127,7 +129,7 @@ def save_m(self):
         np.save(name, self.spin)
 
 
-    def run(self, steps=1000, save_m_steps=100, save_vtk_steps=100):
+    def run(self, steps=1000, save_m_steps=100, save_vtk_steps=100, save_data_steps=1):
 
         if save_m_steps is not None:
             self.save_m()
@@ -139,8 +141,9 @@ def run(self, steps=1000, save_m_steps=100, save_vtk_steps=100):
             self.step = step
             clib.run_mc_step(self.spin, self.random_spin, self.ngbs,
                 self.J, self.D, self._H, self.n, self.T)
-
-            self.saver.save()
+            if save_data_steps is not None:
+                if step % save_data_steps == 0:
+                    self.saver.save()
 
             if save_vtk_steps is not None:
                 if step % save_vtk_steps == 0:
@@ -149,7 +152,7 @@ def run(self, steps=1000, save_m_steps=100, save_vtk_steps=100):
                 if step % save_m_steps == 0:
                     self.save_m()
 
-    	    print("step=%d, skyrmion number=%0.4g"%(self.step, self.skyrmion_number()))
+    	    print("step=%d, skyrmion number=%0.9g"%(self.step, self.skx_num))