Specific heat of doped armchair and zigzag carbon nanotubes

•Theoretical calculation of specific heat of zigzag carbon nanotubes in the context of the Holstein model.•The investigation of specific heat versus electron–phonon interaction.•The investigation of specific heat versus diameters and electronic concentration.

We study the temperature behavior of electronic specific heat of metallic carbon nanotubes in the context of Holstein model Hamiltonian. Green's function approach has been implemented in order to calculate the electronic contribution to the specific heat of the compound. Second order perturbation theory has been used to obtain interacting Green's function of model Hamiltonian. The results show a monotonic increasing behavior for specific heat with temperature for both armchair and zigzag carbon nanotubes. Furthermore, the effect of various electronic concentrations and the electron–phonon coupling strengths on the specific heat has been investigated.