▎ 摘　　要

In the present work, we investigate the possible creation of two-dimensional graphene - like allotropes of thorium and uranium - referred to as thoriumene and uraniumene, respectively. The stable structures have a buckled geometry and are metallic. The in-plane elastic constants for these systems are smaller than those reported for graphene and silicene. The phonon dispersions show positive frequencies, signaling the dynamical stability of the buckled geometries. They also depict acoustic-optical phonon bandgaps, which are 5.25 times larger in uraniumene. A molecular dynamics simulation at 300 K reveals no bond breaking or structural damage, indicating the thermal stability of the materials at room temperature. For light incident within the plane of the structures, absorption occurs in the infrared region (IR). Absorption in the ultraviolet (UV) regime is also conceivable for light incident along the perpendicular (z) direction. Both structures show significant reflectivity coefficients along the whole photon energy range, up to the extreme UV energy of 12 eV. While the major role in stabilizing the structures is buckling, the addition of the spin-orbit coupling only soothes minor negative frequencies present in the vicinity of the Gamma symmetry point. Once synthesized, these novel structures could be exploited in optoelectronic applications, including thin films that entail IR and extreme UV reflectors.