Restructure python bindings, add more core bindings and tests

include/occ/core/elastic_tensor.h

@@ -49,12 +49,15 @@ class ElasticTensor {
   double
   average_poisson_ratio(AveragingScheme avg = AveragingScheme::Hill) const;
 
-  Mat6 voigt_s() const;
-  Mat6 voigt_c() const;
+  const Mat6 &voigt_s() const;
+  const Mat6 &voigt_c() const;
 
   double component(int i, int j, int k, int l) const;
   double &component(int i, int j, int k, int l);
 
+  inline double *data() { return &m_components[0][0][0][0]; }
+  inline double const *data() const { return &m_components[0][0][0][0]; }
+
 private:
   Mat6 m_c;
   Mat6 m_s;

src/core/elastic_tensor.cpp

@@ -231,9 +231,9 @@ double ElasticTensor::average_poisson_ratio(AveragingScheme avg) const {
   return (3 * K - 2 * G) / (2 * (3 * K + G));
 }
 
-Mat6 ElasticTensor::voigt_s() const { return m_s; }
+const Mat6 &ElasticTensor::voigt_s() const { return m_s; }
 
-Mat6 ElasticTensor::voigt_c() const { return m_c; }
+const Mat6 &ElasticTensor::voigt_c() const { return m_c; }
 
 double ElasticTensor::component(int i, int j, int k, int l) const {
   return m_components[i][j][k][l];

src/core/point_group.cpp

@@ -71,6 +71,11 @@ SymOp SymOp::inversion() {
   return SymOp(transformation);
 }
 
+SymOp SymOp::identity() {
+  Mat4 transformation = Mat4::Identity();
+  return SymOp(transformation);
+}
+
 bool is_valid_symop(const SymOp &op, Eigen::Ref<const Mat3N> positions) {
   auto nc = op.apply(positions);
   const size_t N = positions.cols();

src/occpy/__init__.py

@@ -2,10 +2,10 @@
 import site
 import warnings
 from ._occpy import setup_logging, set_data_directory, set_num_threads
-from ._occpy.core import Atom, Element, Molecule, Dimer
-from ._occpy.crystal import Crystal
-from ._occpy.qm import AOBasis, HartreeFock, Shell, Wavefunction
-from ._occpy.dft import DFT
+from .core import Atom, Element, Molecule, Dimer
+from .crystal import Crystal
+from .qm import AOBasis, HartreeFock, Shell, Wavefunction
+from .dft import DFT
 
 # Set up logging first
 setup_logging(0)
@@ -24,12 +24,16 @@
     "Atom",
     "AOBasis",
     "calculate_crystal_growth_energies",
+    "core",
+    "crystal",
     "Crystal",
+    "dft",
     "DFT",
     "Dimer",
     "Element",
     "HartreeFock",
     "Molecule",
+    "qm",
     "set_data_directory",
     "set_num_threads",
     "setup_logging",

src/occpy/core/__init__.py

@@ -0,0 +1 @@
+from .._occpy.core import *

src/occpy/crystal/__init__.py

@@ -0,0 +1 @@
+from .._occpy.crystal import *

src/occpy/dft/__init__.py

@@ -0,0 +1 @@
+from .._occpy.dft import *

src/occpy/qm/__init__.py

@@ -0,0 +1 @@
+from .._occpy.qm import *