Stable configurations and electronic structures of hydrogenated graphyne

• Published in: Computational materials science 2014-08, Vol.91, p.274-278
• Main Authors: Ma, ShuangYing, Zhang, C.X., He, Junjie, Zhou, Pan, Zhang, K.W., He, Chaoyu, Sun, L.Z.
• Format: Article
• Language: English
• Subjects: Carbon; Condensed matter: electronic structure, electrical, magnetic, and optical properties; Density functional theory; Depth indicators; Devices; Electron states and collective excitations in thin films, multilayers, quantum wells, mesoscopic and nanoscale systems; Electronic structure; Electronic structure and electrical properties of surfaces, interfaces, thin films and low-dimensional structures; Electronic structure of nanoscale materials : clusters, nanoparticles, nanotubes, and nanocrystals; Exact sciences and technology; Free energy; Graphyne; Hydrogen atoms; Hydrogenation; Mathematical analysis; Physics; Stability; Thin films and multilayers
• ISSN: 0927-0256; 1879-0801
• DOI: 10.1016/j.commatsci.2014.05.006

[Display omitted] •Dynamical stability of fully hydrogenated graphyne is studied.•Zero-point energy is essential for determining the stability of hydrogenated graphyne.•Band-gap undergoes direct–indirect–direct transition with the increase of H coverage. First-principles calculations are performed to investigate dynamical stability of hydrogenated graphyne and its electronic structures. We find that the zero point energy (ZPE) is important in evaluating the stability of hydrogenated graphyne. Based on the results of formation enthalpy, the hydrogenated configuration with only sp3 carbon atoms (eHH) is more stable than that with each carbon atom passivated by single hydrogen atom (eH). However, the Helmholtz free energy as functions of temperature indicates that eH is more favorable than eHH below 670K. Based on DFT-based phonon spectrum calculations, the dynamical stability of eHH and eH is confirmed. Of particular interest is that the band-gap feature of graphyne undergoes direct–indirect–direct transition with the increase in the concentration of hydrogen. The results indicate that eHH is favorable for the applications in the field of deep ultraviolet light-emitting devices.