The present paper analyzes the density of states (DOS), and optical conductivity of the non-hexagonal S-graphene system as a stable allotrope of carbon in the presence of an external exchange magnetic field (EEMF) using the tight-binding (TB) approach. Our results show that with the increase of the EEMF, the energy band gap decreases, and Van Hove’s singularity is divided into two separate peaks. Also, the optical conductivity of the S-graphene sheet has been explored by applyingthe current–current time correlation func- tion in the Kubo formula from the linear response theory and also using Green’s function approach. On the other hand, we reported the frequency dependence of optical conductiv- ity for various values of the EEMF, hole and electron doping, and temperature, which have been examined in detail. The results show that, in the zero frequency range, different tem- peratures lead to the appearance of a Drude response, which is the result of the intra-band transfer of electrons. Also, the dispersion speed in the conduction band (due to the increase in electron density) increases with the increase in electron doping, which causes the Pauli blocking phenomenon and as a result decreases optical absorption. Due to the raise of intra-band and inter-band electronic transitions, optical absorption is promoted with the increase of absorption frequency.
