title: DFT and TB study of the geometry of hydrogen adsorbed on graphynes.
abstract: Using density-functional calculations (DFT) and a tight-binding model, we investigate the origin of distinct favorable geometries which depend on the type of graphyne used. The change in the H geometry is described in terms of the tuning of the hopping between sp(2)-bonded C atoms and sp-bonded C atoms hybridized with the H atoms. We find that the different preferred geometry for each type of graphyne is associated with the electronic effects due to different symmetries rather than a steric effect minimizing the repulsive interaction between the H atoms. The band gaps are significantly tuned as the hopping varies, except in α-graphyne, in agreement with the result of our previous DFT study (Koo J et al 2013 J. Phys. Chem. C 117 11960). Our model can be used to describe the geometry and electronic properties of hydrogenated graphynes.
authors.affiliation: School of Physics, Konkuk University, Seoul 143-701, Korea. CNR-IOM-Democritos National Simulation Centre and International School for Advanced Studies (SISSA), Via Bonomea 265, I-34136, Trieste, Italy. School of General Studies, Kangwon National University, Samcheok-Si, Kangwon-Do 245-711, Korea.
authors.forename: Hunpyo
authors.initials: H
authors.lastname: Lee
authors.forename: Jahyun
authors.initials: J
authors.lastname: Koo
authors.forename: Massimo
authors.initials: M
authors.lastname: Capone
authors.forename: Yongkyung
authors.initials: Y
authors.lastname: Kwon
authors.forename: Hoonkyung
authors.initials: H
authors.lastname: Lee