new DiffuseReflectivityModel in simpack

new code for the simulation of diffuse x-ray reflectivity of multilayers

CHANGES.txt

@@ -1,3 +1,4 @@
+* simulation code for diffuse X-ray reflectivity
 * more flexibility in defining materials Wyckoff positions
 * convenience function to calculate diffracted intensities of thin films to
   compare various Bragg peaks (coplanar diffraction geoemetry)

examples/simpack_xrr_diffuse.py

@@ -0,0 +1,55 @@
+# This file is part of xrayutilities.
+#
+# xrayutilities is free software; you can redistribute it and/or modify
+# it under the terms of the GNU General Public License as published by
+# the Free Software Foundation; either version 2 of the License, or
+# (at your option) any later version.
+#
+# This program is distributed in the hope that it will be useful,
+# but WITHOUT ANY WARRANTY; without even the implied warranty of
+# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+# GNU General Public License for more details.
+#
+# You should have received a copy of the GNU General Public License
+# along with this program; if not, see <http://www.gnu.org/licenses/>.
+#
+# Copyright (C) 2018 Dominik Kriegner <dominik.kriegner@gmail.com>
+
+import time
+
+import xrayutilities as xu
+from matplotlib.pylab import *
+
+sub = xu.simpack.Layer(xu.materials.Si, inf, roughness=1, lat_correl=100)
+lay1 = xu.simpack.Layer(xu.materials.Si, 200, roughness=1, lat_correl=200)
+lay2 = xu.simpack.Layer(xu.materials.Ge, 70, roughness=3, lat_correl=50)
+
+ls = xu.simpack.LayerStack('SL 5', sub+5*(lay2+lay1))
+
+alphai = arange(0.17, 2, 0.001)
+
+print("calculate method=1, H=1, vert=0")
+start = time.time()
+m = xu.simpack.DiffuseReflectivityModel(ls, sample_width=10, beam_width=1,
+                                        energy='CuKa1', vert_correl=1000,
+                                        vert_nu=0, H=1, method=1, vert_int=0)
+d1 = m.simulate(alphai)
+print("elapsed time: %.4f" % (time.time() - start))
+
+
+print("calculate method=2, H=1, vert=0")
+start = time.time()
+m = xu.simpack.DiffuseReflectivityModel(ls, sample_width=10, beam_width=1,
+                                        energy='CuKa1', vert_correl=1000,
+                                        vert_nu=0, H=1, method=2, vert_int=0)
+d2 = m.simulate(alphai)
+print("elapsed time: %.4f" % (time.time() - start))
+
+figure()
+semilogy(alphai, d1, label='method=1')
+semilogy(alphai, d2, label='method=2')
+
+legend()
+xlabel('incidence angle (deg)')
+ylabel('intensity (arb. u.)')
+tight_layout()

tests/test_xrrdiffuse.py

@@ -0,0 +1,65 @@
+# This file is part of xrayutilities.
+#
+# xrayutilities is free software; you can redistribute it and/or modify
+# it under the terms of the GNU General Public License as published by
+# the Free Software Foundation; either version 2 of the License, or
+# (at your option) any later version.
+#
+# This program is distributed in the hope that it will be useful,
+# but WITHOUT ANY WARRANTY; without even the implied warranty of
+# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+# GNU General Public License for more details.
+#
+# You should have received a copy of the GNU General Public License
+# along with this program; if not, see <http://www.gnu.org/licenses/>.
+#
+# Copyright (C) 2018 Dominik Kriegner <dominik.kriegner@gmail.com>
+
+import os
+import unittest
+
+import numpy
+import xrayutilities as xu
+
+
+class Test_DiffuseReflectivityModel(unittest.TestCase):
+    diffmax = 2e-6
+    # define used layer stack
+    sub = xu.simpack.Layer(xu.materials.Si, numpy.inf, roughness=1,
+                           lat_correl=100)
+    lay1 = xu.simpack.Layer(xu.materials.Si, 200, roughness=1, lat_correl=200)
+    lay2 = xu.simpack.Layer(xu.materials.Ge, 70, roughness=3, lat_correl=50)
+
+    ls = xu.simpack.LayerStack('SL 5', sub+5*(lay2+lay1))
+
+    # simulation parameters
+    kwargs = dict(sample_width=10, beam_width=1, energy='CuKa1',
+                  vert_correl=1000, vert_nu=0, H=1, method=1, vert_int=0)
+
+    @classmethod
+    def setUpClass(cls):
+        cls.m1 = xu.simpack.DiffuseReflectivityModel(cls.ls, **cls.kwargs)
+        cls.kwargs['H'] = cls.kwargs['H'] - xu.config.EPSILON
+        cls.m2 = xu.simpack.DiffuseReflectivityModel(cls.ls, **cls.kwargs)
+        cls.kwargs['H'] = 1
+        cls.kwargs['method'] = 2
+        cls.m3 = xu.simpack.DiffuseReflectivityModel(cls.ls, **cls.kwargs)
+        cls.ai = numpy.arange(0.3, 2, 0.005)
+
+    def test_Calculation(self):
+        sim = self.m1.simulate(self.ai)
+        self.assertEqual(len(sim), len(self.ai))
+        self.assertTrue(numpy.all(sim >= 0))
+
+    def test_Consistency(self):
+        # calc models
+        sim1 = self.m1.simulate(self.ai)
+        sim2 = self.m2.simulate(self.ai)
+        sim3 = self.m3.simulate(self.ai)
+
+        self.assertTrue((numpy.mean(sim1) - numpy.mean(sim2)) < self.diffmax)
+        self.assertTrue((numpy.mean(sim1) - numpy.mean(sim3)) < self.diffmax)
+
+
+if __name__ == '__main__':
+    unittest.main()

xrayutilities/simpack/__init__.py

@@ -13,7 +13,7 @@
 # You should have received a copy of the GNU General Public License
 # along with this program; if not, see <http://www.gnu.org/licenses/>.
 #
-# Copyright (C) 2016 Dominik Kriegner <dominik.kriegner@gmail.com>
+# Copyright (C) 2016-2018 Dominik Kriegner <dominik.kriegner@gmail.com>
 """
 simulation subpackage of xrayutilities.
 
@@ -36,6 +36,7 @@
 from .models import KinematicalModel
 from .models import KinematicalMultiBeamModel
 from .models import SpecularReflectivityModel
+from .models import DiffuseReflectivityModel
 from .models import SimpleDynamicalCoplanarModel
 from .models import DynamicalModel