The dielectric constant calculated by DielectricCylinder on the Z-axis is different from the system length

Our system is composed of carbon nanotubes filled with water molecules, and the length of the carbon nanotubes is 17nm. The horizontal axis calculated by the DielectricCylinder is not the length of this system. May I ask why this is the case? Below are our code and result graphs.

`import MDAnalysis import matplotlib.pyplot as plt import maicos

u = MDAnalysis.Universe("D:/jisuanwuli/vmd1/0Na-lizi-shui/cnt+chunshui.data", "D:/vmd1/cnt_water.lammpstrj",topology_format="DATA",format="LAMMPSDUMP", lammps_coordinate_convention="auto", dt=2)

water = u.select_atoms("byres type 3 and bonded type 2")

analysis_obj = maicos.DielectricCylinder(water,bin_width=0.1,refgroup=water,unwrap=True) analysis_obj.run(step=60)

fig, ax = plt.subplots(2, sharex=True)

z = analysis_obj.results.bin_pos

ax[0].plot(z, analysis_obj.results.eps_r) ax[1].plot(z, analysis_obj.results.eps_z)

ax[0].set_ylabel(r"\varepsilon^{-1}_{\perp} - 1") ax[1].set_ylabel(r"\varepsilon_{\parallel} - 1")

ax[1].set_xlabel(r"z")

ax[0].set_xlim([-5, 15]) ax[1].set_xlim([-5, 15])

fig.tight_layout() plt.show()`