We report the band structures of first stage potassium intercalated graphyn
e using the optimized geometries. The calculation was carried out using the
full-potential linear-combination-of-atomic-orbitals method. The optimized
distance between two graphyne layers sandwiching the intercalate layer is
shorter than typical graphite intercalation compounds. These intercalation
compounds are metallic. The character of the band around the Fermi level at
Gamma point is C2p(z). The band with the character of K4s lies about 2.4 e
V higher than the Fermi level at Gamma point for the compound intercalating
one potassium in a unit cell, while that lies about 0.89 eV higher than th
e Fermi level at Gamma point for intercalating two potassium in a unit cell
. Further we refer the amount of charge transfer between potassium and carb
on atoms.