Fig. 1. Crystal structure of honeycomb lattice with two different sublattices. Here a₁ and a₂ are the primitive unit cell vectors.

Fig. 2. Imaginary part of dynamical charge susceptibility (Imχ(q₀,ω)) of undoped armchair nanotube (5,5) as a function of normalized frequency ω/t for different values of gap parameter Δ/t for fixed temperature k_BT/t = 0.05. The magnetic field is assumed to be zero. The electron–phonon coupling constant has been fixed as g/t = 0.2.

Fig. 3. Imaginary part of dynamical charge susceptibility (Imχ(q₀,ω)) of doped armchair nanotube (5,5) as a function of normalized frequency ω/t for different values of chemical potential ω/t for fixed temperature k_BT/t = 0.05. The magnetization is assumed to be zero. The electron–phonon coupling constant has been fixed as g/t = 0.2. The gap parameter has been fixed at Δ/t = 0.8.

Fig. 4. Imaginary part of dynamical charge susceptibility (Imχ(q₀,ω)) of undoped armchair nanotube (5,5) as a function of normalized frequency ω/t for different values of next nearest neighbor hopping amplitude t′/t for fixed temperature k_BT/t = 0.05. The magnetization is assumed to be zero. The electron–phonon coupling constant has been fixed as g/t = 0.2. The gap parameter has been fixed at Δ/t = 0.8.

Fig. 5. Static charge susceptibility (S(q₀,T)) of undoped armchair nanotube (5,5) as a function of normalized temperature k_BT/t for different values of gap parameter Δ/t in the absence of instantanous magnetization. The normalized electron–phonon coupling constant has been fixed as g/t = 0.05.

Fig. 6. Static charge susceptibility (S(q₀,T)) of undoped armchair nanotube (5,5) as a function of normalized temperature k_BT/t for different electron–phonon coupling strength g/t in the absence of instantaneous magnetization. The normalized gap parameter has been fixed as Δ/t = 0.8.

Fig. 7. Static charge susceptibility (S(q₀,T)) of undoped armchair nanotube (5,5) as a function of normalized temperature k_BT/t for different magnetization values of M at fixed g/t = 0.2. The normalized gap parameter has been fixed as Δ/t = 0.8.

Fig. 8. Static charge susceptibility (S(q₀,T)) of undoped armchair nanotube (5,5) as a function of normalized temperature k_BT/t for different normalized chemical potential values μ/t at fixed g/t = 0.2. The normalized gap parameter has been fixed as Δ/t = 0.8.