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 alpha-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.
|Titolo:||DFT and TB study of the geometry of hydrogen adsorbed on graphynes|
|Autori:||Lee, H.; Koo, J.; Capone, M.; Kwon, Y.; Lee, H.|
|Rivista:||JOURNAL OF PHYSICS. CONDENSED MATTER|
|Data di pubblicazione:||2014|
|Digital Object Identifier (DOI):||10.1088/0953-8984/26/38/385301|
|Appare nelle tipologie:||1.1 Journal article|