def _calc_temp(self, V_a, T0=None):
        T0, = self.eos_mod.get_param_values(param_names=['T0'], overrides=[T0])
        V0, gamma0, gamma_inf, beta = self.eos_mod.get_param_values(
            param_names=['V0','gamma0','gamma_inf','beta'])

        gamma_a = self._calc_gamma(V_a)
        x = V_a/V0
        T_a = T0*x**(-gamma_inf)*np.exp((gamma0-gamma_inf)/beta*(1-x**beta))

        return T_a