▎ 摘　　要

We have calculated the electronic properties of graphene and SiC, GeC and SnC monolayers in a two-dimensional graphene-like honeycomb structure under various strained conditions using first principles calculations based on density functional theory and the quasiparticle GW approximation. Our results show that the indirect-direct band gap transition of group-IV carbides can be tuned by strain, which indicates a possible new route for tailoring the electronic properties of ultrathin nanofilms through strain engineering.