Finds all the kinks in mixing ratio where reaction products changes
        along the tie line of composition self.c1 and composition self.c2.

        Returns:
            Zip object of tuples (index, mixing ratio,
                                  reaction energy per atom in eV/atom,
                                  reaction formula,
                                  reaction energy per mol of reaction
                                  formula in kJ/mol).

def get_kinks(self):
        """
        Finds all the kinks in mixing ratio where reaction products changes
        along the tie line of composition self.c1 and composition self.c2.

        Returns:
            Zip object of tuples (index, mixing ratio,
                                  reaction energy per atom in eV/atom,
                                  reaction formula,
                                  reaction energy per mol of reaction
                                  formula in kJ/mol).
        """
        c1_coord = self.pd.pd_coords(self.comp1)
        c2_coord = self.pd.pd_coords(self.comp2)
        n1 = self.comp1.num_atoms
        n2 = self.comp2.num_atoms
        critical_comp = self.pd.get_critical_compositions(self.comp1,
                                                          self.comp2)
        x_kink, energy_kink, react_kink, energy_per_rxt_formula = \
            [], [], [], []
        if all(c1_coord == c2_coord):
            x_kink = [0, 1]
            energy_kink = [self._get_energy(x) for x in x_kink]
            react_kink = [self._get_reaction(x) for x in x_kink]
            num_atoms = [(x * self.comp1.num_atoms +
                          (1-x) * self.comp2.num_atoms) for x in x_kink]
            energy_per_rxt_formula = [energy_kink[i] *
                                      self._get_elmt_amt_in_rxt(
                                          react_kink[i]) /
                                      num_atoms[i] *
                                      InterfacialReactivity.EV_TO_KJ_PER_MOL
                                      for i in range(2)]
        else:
            for i in reversed(critical_comp):
                # Gets mixing ratio x at kinks.
                c = self.pd.pd_coords(i)
                x = np.linalg.norm(c - c2_coord) / \
                    np.linalg.norm(c1_coord - c2_coord)
                # Modifies mixing ratio in case compositions self.comp1 and
                # self.comp2 are not normalized.
                x = x * n2 / (n1 + x * (n2 - n1))
                n_atoms = x * self.comp1.num_atoms \
                    + (1-x) * self.comp2.num_atoms
                # Converts mixing ratio in comp1 - comp2 tie line to that in
                # c1 - c2 tie line.
                x_converted = InterfacialReactivity._convert(
                    x, self.factor1, self.factor2)
                x_kink.append(x_converted)
                # Gets reaction energy at kinks
                normalized_energy = self._get_energy(x)
                energy_kink.append(normalized_energy)
                # Gets balanced reaction at kinks
                rxt = self._get_reaction(x)
                react_kink.append(rxt)
                rxt_energy = normalized_energy * \
                    self._get_elmt_amt_in_rxt(rxt) / \
                    n_atoms
                energy_per_rxt_formula.append(
                    rxt_energy *
                    InterfacialReactivity.EV_TO_KJ_PER_MOL)
        index_kink = range(1, len(critical_comp)+1)
        return zip(index_kink, x_kink, energy_kink, react_kink,
                   energy_per_rxt_formula)