The local field intensities for different tip heights obtained by the conventional theory ((a), (c), (e), (g) for d = 1.6 nm, 2.0 nm, 2.4 nm, 3.0 nm) and the modified theory considering the molecular self-interaction (polarizability β = 1.5β₀, (b), (d), (f), (h) for d = 1.6 nm, 2.0 nm, 2.4 nm, 3.0 nm)). The radius of the tip apex is R = 10 nm and the molecular locates at r_z = 1.0 nm.