impl Residual for PcSaftFunctional {
    fn compute_max_density(&self, moles: &Array1<f64>) -> f64 {
        // moved from the implementation of `HelmholtzEnergyFunctional`
    }

    fn residual_helmholtz_energy_contributions<D: DualNum<f64> + Copy + ScalarOperand>(
        &self,
        state: &StateHD<D>,
    ) -> Vec<(String, D)> {
        self.evaluate_bulk(state)
    }
}