def read_igpar(self):
        """
        Renders accessible:
            er_ev = e<r>_ev (dictionary with Spin.up/Spin.down as keys)
            er_bp = e<r>_bp (dictionary with Spin.up/Spin.down as keys)
            er_ev_tot = spin up + spin down summed
            er_bp_tot = spin up + spin down summed
            p_elc = spin up + spin down summed
            p_ion = spin up + spin down summed

        (See VASP section "LBERRY,  IGPAR,  NPPSTR,  DIPOL tags" for info on
        what these are).
        """

        # variables to be filled
        self.er_ev = {}  # will  be  dict (Spin.up/down) of array(3*float)
        self.er_bp = {}  # will  be  dics (Spin.up/down) of array(3*float)
        self.er_ev_tot = None  # will be array(3*float)
        self.er_bp_tot = None  # will be array(3*float)
        self.p_elec = None
        self.p_ion = None
        try:
            search = []

            # Nonspin cases
            def er_ev(results, match):
                results.er_ev[Spin.up] = np.array(map(float,
                                                      match.groups()[1:4])) / 2
                results.er_ev[Spin.down] = results.er_ev[Spin.up]
                results.context = 2

            search.append([r"^ *e<r>_ev=\( *([-0-9.Ee+]*) *([-0-9.Ee+]*) "
                           r"*([-0-9.Ee+]*) *\)",
                           None, er_ev])

            def er_bp(results, match):
                results.er_bp[Spin.up] = np.array([float(match.group(i))
                                                   for i in range(1, 4)]) / 2
                results.er_bp[Spin.down] = results.er_bp[Spin.up]

            search.append([r"^ *e<r>_bp=\( *([-0-9.Ee+]*) *([-0-9.Ee+]*) "
                           r"*([-0-9.Ee+]*) *\)",
                           lambda results, line: results.context == 2, er_bp])

            # Spin cases
            def er_ev_up(results, match):
                results.er_ev[Spin.up] = np.array([float(match.group(i))
                                                   for i in range(1, 4)])
                results.context = Spin.up

            search.append([r"^.*Spin component 1 *e<r>_ev=\( *([-0-9.Ee+]*) "
                           r"*([-0-9.Ee+]*) *([-0-9.Ee+]*) *\)",
                           None, er_ev_up])

            def er_bp_up(results, match):
                results.er_bp[Spin.up] = np.array([float(match.group(1)),
                                                   float(match.group(2)),
                                                   float(match.group(3))])

            search.append([r"^ *e<r>_bp=\( *([-0-9.Ee+]*) *([-0-9.Ee+]*) "
                           r"*([-0-9.Ee+]*) *\)",
                           lambda results,
                                  line: results.context == Spin.up, er_bp_up])

            def er_ev_dn(results, match):
                results.er_ev[Spin.down] = np.array([float(match.group(1)),
                                                     float(match.group(2)),
                                                     float(match.group(3))])
                results.context = Spin.down

            search.append([r"^.*Spin component 2 *e<r>_ev=\( *([-0-9.Ee+]*) "
                           r"*([-0-9.Ee+]*) *([-0-9.Ee+]*) *\)",
                           None, er_ev_dn])

            def er_bp_dn(results, match):
                results.er_bp[Spin.down] = np.array([float(match.group(i))
                                                     for i in range(1, 4)])

            search.append([r"^ *e<r>_bp=\( *([-0-9.Ee+]*) *([-0-9.Ee+]*) "
                           r"*([-0-9.Ee+]*) *\)",
                           lambda results,
                                  line: results.context == Spin.down, er_bp_dn])

            # Always present spin/non-spin
            def p_elc(results, match):
                results.p_elc = np.array([float(match.group(i))
                                          for i in range(1, 4)])

            search.append([r"^.*Total electronic dipole moment: "
                           r"*p\[elc\]=\( *([-0-9.Ee+]*) *([-0-9.Ee+]*) "
                           r"*([-0-9.Ee+]*) *\)", None, p_elc])

            def p_ion(results, match):
                results.p_ion = np.array([float(match.group(i))
                                          for i in range(1, 4)])

            search.append([r"^.*ionic dipole moment: "
                           r"*p\[ion\]=\( *([-0-9.Ee+]*) *([-0-9.Ee+]*) "
                           r"*([-0-9.Ee+]*) *\)", None, p_ion])

            self.context = None
            self.er_ev = {Spin.up: None, Spin.down: None}
            self.er_bp = {Spin.up: None, Spin.down: None}

            micro_pyawk(self.filename, search, self)

            if self.er_ev[Spin.up] is not None and \
                    self.er_ev[Spin.down] is not None:
                self.er_ev_tot = self.er_ev[Spin.up] + self.er_ev[Spin.down]

            if self.er_bp[Spin.up] is not None and \
                    self.er_bp[Spin.down] is not None:
                self.er_bp_tot = self.er_bp[Spin.up] + self.er_bp[Spin.down]

        except:
            self.er_ev_tot = None
            self.er_bp_tot = None
            raise Exception("IGPAR OUTCAR could not be parsed.")