add atomistic version of stt

Author: Weiwei Wang

fidimag/atomistic/llg.py

@@ -156,6 +156,8 @@ def set_mu_s(self, value):
                 # Set the neighbour index to -1 for sites with mu_s = 0
                 self.mesh.neighbours[self.mesh.neighbours == i] = -1
 
+        self.mu_s_const = np.max(self._mu_s)
+
     mu_s = property(get_mu_s, set_mu_s)
 
     def add(self, interaction, save_field=False):

fidimag/atomistic/llg_stt.py

@@ -0,0 +1,89 @@
+from __future__ import division
+
+import fidimag.extensions.clib as clib
+import numpy as np
+
+from .llg import LLG
+import fidimag.common.helper as helper
+import fidimag.common.constant as const
+
+
+class LLG_STT(LLG):
+
+    def __init__(self, mesh, name='unnamed'):
+        """Simulation object.
+
+        *Arguments*
+
+          name : the Simulation name (used for writing data files, for examples)
+
+        """
+        super(LLG_STT, self).__init__(mesh, name=name)
+
+        self.field_stt = np.zeros(3 * self.n)
+
+        self._jx = np.zeros(self.n, dtype=np.float)
+        self._jy = np.zeros(self.n, dtype=np.float)
+
+        self.p = 0.5
+        self.beta = 0
+        self.update_j_fun = None
+
+        # FIXME: change the u0 to spatial
+        self.u0 = const.g_e * const.mu_B / (2 * const.c_e)
+
+    def get_jx(self):
+        return self._jx
+
+    def set_jx(self, value):
+        self._jx[:] = helper.init_scalar(value, self.mesh)
+
+    jx = property(get_jx, set_jx)
+
+    def get_jy(self):
+        return self._jy
+
+    def set_jy(self, value):
+        self._jy[:] = helper.init_scalar(value, self.mesh)
+
+    jy = property(get_jy, set_jy)
+
+    def sundials_rhs(self, t, y, ydot):
+
+        self.t = t
+
+        # already synchronized when call this funciton
+        # self.spin[:]=y[:]
+
+        self.compute_effective_field(t)
+
+        if self.update_j_fun is not None:
+            clib.compute_stt_field(self.spin,
+                                   self.field_stt,
+                                   self._jx * self.update_j_fun(t),
+                                   self._jy * self.update_j_fun(t),
+                                   self.mesh.dx * self.mesh.unit_length,
+                                   self.mesh.dy * self.mesh.unit_length,
+                                   self.mesh.neighbours,
+                                   self.n
+                                   )
+        else:
+            clib.compute_stt_field(self.spin,
+                                   self.field_stt,
+                                   self._jx,
+                                   self._jy,
+                                   self.mesh.dx * self.mesh.unit_length,
+                                   self.mesh.dy * self.mesh.unit_length,
+                                   self.mesh.neighbours,
+                                   self.n
+                                   )
+
+        clib.compute_llg_stt_rhs(ydot,
+                                 self.spin,
+                                 self.field,
+                                 self.field_stt,
+                                 self.alpha,
+                                 self.beta,
+                                 self.u0 * self.p / self.Ms_const,
+                                 self.gamma,
+                                 self.n)

…ag/atomistic/llg_stt_slonczewski_type.py fidimag/atomistic/llg_stt_cpp.pyfidimag/atomistic/llg_stt_slonczewski_type.py renamed to fidimag/atomistic/llg_stt_cpp.py fidimag/atomistic/llg_stt_slonczewski_type.py renamed to fidimag/atomistic/llg_stt_cpp.py

@@ -9,7 +9,7 @@
 import fidimag.common.helper as helper
 
 
-class LLG_STT_Slonczewski(LLG):
+class LLG_STT_CPP(LLG):
 
     def __init__(self, mesh, name='unnamed'):
         """Simulation object.
@@ -19,7 +19,7 @@ def __init__(self, mesh, name='unnamed'):
           name : the Simulation name (used for writing data files, for examples)
 
         """
-        super(LLG_STT_Slonczewski, self).__init__(mesh, name=name)
+        super(LLG_STT_CPP, self).__init__(mesh, name=name)
 
         self._p = np.zeros(3 * self.n, dtype=np.float)
         self._a_J = np.zeros(self.n, dtype=np.float)

fidimag/atomistic/sim.py

@@ -1,11 +1,13 @@
 from .llg import LLG
 from .sllg import SLLG
-from .llg_stt_slonczewski_type import LLG_STT_Slonczewski
+from .llg_stt import LLG_STT
+from .llg_stt_cpp import LLG_STT_CPP
 
 
 KNOWN_DRIVERS = {'llg': LLG,
                  'sllg': SLLG,
-                 'slonczewski': LLG_STT_Slonczewski
+                 'llg_stt': SLLG_STT,
+                 'llg_stt_cpp': LLG_STT_CPP
 		}
 
 

fidimag/micro/llg_stt.py

@@ -30,7 +30,8 @@ def __init__(self, mesh, name='unnamed'):
         self.update_j_fun = None
 
         # FIXME: change the u0 to spatial
-        self.u0 = const.g_e * const.mu_B / (2 * const.c_e)
+        v = self.mesh.dx* self.mesh.dy * self.mesh.dz * (self.mesh.unit_length**3)
+        self.u0 = const.g_e * const.mu_B / (2 * const.c_e) * v
 
     def get_jx(self):
         return self._jx
@@ -84,6 +85,6 @@ def sundials_rhs(self, t, y, ydot):
                                  self.field_stt,
                                  self.alpha,
                                  self.beta,
-                                 self.u0 * self.p / self.Ms_const,
+                                 self.u0 * self.p / self.mu_s_constant,
                                  self.gamma,
                                  self.n)