def METHOD_NAME(args):
    volumes = []
    energy_sigma0 = []
    free_energies = []
    temperatures = None
    for filename in args.filenames:
        vxml = parse_vasprunxml(filename)
        weights = vxml.k_weights
        eigenvalues = vxml.eigenvalues[:, :, :, 0]
        n_electrons = vxml.NELECT
        energy = vxml.energies[-1, 1]
        temps, fe = get_free_energy_at_T(
            args.tmin, args.tmax, args.tstep, eigenvalues, weights, n_electrons
        )
        volumes.append(vxml.volume[-1])
        energy_sigma0.append(energy)
        free_energies.append(energy - fe[0] + fe)
        if temperatures is None:
            temperatures = temps
        else:
            assert (np.abs(temperatures - temps) < 1e-5).all()
    lines_fe = []
    lines_fe.append(("# volume:  " + " %15.8f" * len(volumes)) % tuple(volumes))
    lines_fe.append("#    T(K)     Free energies")
    lines_fe += get_free_energy_lines(temperatures, np.transpose(free_energies))
    lines_ev = ["#   cell volume        energy of cell other than phonon"]
    lines_ev += ["%20.8f %20.8f" % (v, e) for v, e in zip(volumes, energy_sigma0)]
    return lines_fe, lines_ev