Computes reaction energy in eV/atom at mixing ratio x : (1-x) for
        self.comp1 : self.comp2.

        Args:
            x (float): Mixing ratio x of reactants, a float between 0 and 1.

        Returns:
            Reaction energy.

def _get_energy(self, x):
        """
        Computes reaction energy in eV/atom at mixing ratio x : (1-x) for
        self.comp1 : self.comp2.

        Args:
            x (float): Mixing ratio x of reactants, a float between 0 and 1.

        Returns:
            Reaction energy.
        """
        return self.pd.get_hull_energy(self.comp1 * x + self.comp2 * (1-x)) - \
            self.e1 * x - self.e2 * (1-x)