In real experiment, we should also take the 3D bulk screening effect into account even though we deal with 1D case like the single filament. The Thomas–Fermi screening has been applied to an electron gas confined to a filament and a coaxial cylinder. For a K 2 Pt(CN) 4 Cl 0.32 ·2.6H 2 0 filament, it was found that the potential within the region between the filament and cylinder varies as e − − k e f f r / r and its effective screening length is about 10 times that of metallic platinum.