Added class ElectronicStructure

Class ElectronicStructure is intended for the internal representation
of the band structure and raw projector data from VASP.
In addition, its purpose is to perform a simple consistency check
of the input VASP data (as they are read from different files).

python/converters/vasp/python/elstruct.py

@@ -0,0 +1,73 @@
+
+import numpy as np
+
+class ElectronicStructure:
+    """
+    Class containing electronic structure data.
+
+    **Parameters:**
+
+    - *natom* (int) : total number of atoms
+    - *nktot* (int) : total number of `k`-points
+    - *nband* (int) : total number of bands
+    - *nspin* (int) : spin-polarization
+    - *nc_flag* (True/False) : non-collinearity flag
+    - *efermi* (float) : Fermi level read from DOSCAR
+    - *proj_raw* (array[complex]) : raw projectors from PLOCAR
+    - *eigvals* (array[float]) : KS eigenvalues
+    - *kmesh* (dict) : parameters of the `k`-mesh
+    - *structure* (dict) : parameters of the crystal structure
+    - *symmetry* (dict) : paramters of symmetry
+
+    When the object is created a simple consistency check
+    of the data coming from different VASP files is performed. 
+    """
+
+    def __init__(self, vasp_data):
+        self.natom = vasp_data.poscar.nq
+        self.nktot = vasp_data.kpoints.nktot
+
+        self.kmesh = {'nktot': self.nktot}
+        self.kmesh['kpoints'] = vasp_data.kpoints.kpts
+        self.kmesh['kwights'] = vasp_data.eigenval.kwghts
+        try:
+            self.kmesh['ntet'] = vasp_data.kpoints.ntet
+            self.kmesh['itet'] = vasp_data.kpoints.itet
+            self.kmesh['volt'] = vasp_data.kpoints.volt
+        except NameError:
+            pass
+
+# Note that one should not subtract this Fermi level from eigenvalues
+# here because the true Fermi level might be provided by conf-file
+# (for instance, for spaghetti calculations)
+        self.efermi = vasp_data.doscar.efermi
+
+# Note that the number of spin-components of projectors might be different from those
+# of bands in case of non-collinear calculations
+        self.nspin = vasp_data.plocar.params['ns']
+        self.nc_flag = vasp_data.plocar.params['nc_flag'] == 1
+
+        self.nband = vasp_data.eigenval.nband
+
+        self.eigvals = vasp_data.eigenval.eigs
+
+# For later use it is more convenient to use a different order of indices
+# [see ProjectorGroup.orthogonalization()]
+        self.proj_raw = vasp_data.plocar.plo.transpose((0, 1, 2, 4, 3))
+
+# Check that the number of atoms is the same in PLOCAR and POSCAR
+        natom_plo = vasp_data.plocar.params['nion']
+        assert natom_plo == self.natom, "PLOCAR is inconsistent with POSCAR (number of atoms)"
+
+# Check that the number of k-points is the same in all files
+        nk_plo = vasp_data.plocar.params['nk']
+        assert nk_plo == self.nktot, "PLOCAR is inconsistent with IBZKPT (number of k-points)"
+        nk_eig = vasp_data.eigenval.nktot
+        assert nk_eig == self.nktot, "PLOCAR is inconsistent with EIGENVAL (number of k-points)"
+
+# Check that the number of band is the same in PLOCAR and EIGENVAL
+        nb_plo = vasp_data.plocar.params['nb']
+        assert nb_plo == self.nband, "PLOCAR is inconsistent with EIGENVAL (number of bands)"
+
+
+