▎ 摘　　要

Using a two-band tight-binding Harrison model and Green's function technique, the influences of both localized sigma and delocalized pi electrons on the density of states, the Pauli paramagnetic susceptibility, and the heat capacity of a graphene sheet are investigated. We witness an extension in the bandwidth and an increase in the number of Van-Hove singularities as well. As a notable point, besides the magnetic nature which includes diamagnetism in graphene-based nanosystems, a paramagnetic behavior associated with the itinerant pi electrons could be occurred. Further, we report a Schottky anomaly in the heat capacity. This study asserts that the contribution of both sigma and pi electrons play dominant roles in the mentioned physical quantities. (C) 2015 Elsevier B.V. All rights reserved,