  The two-dimensional graphene-like carbon allotrope, graphyne, has been
recently fabricated and exhibits many interesting electronic properties. In
this work, we investigate the thermoelectric properties of {\gamma}-graphyne by
performing first-principles calculations combined with Boltzmann transport
theory for both electron and phonon. The carrier relaxation time is accurately
evaluated from the ultra-dense electron-phonon coupling matrix elements
calculated by adopting the density functional perturbation theory and Wannier
interpolation, rather than the generally used deformation potential theory
which only considers the electron-acoustic phonon scattering. It is found that
the thermoelectric performance of {\gamma}-graphyne exhibits a strong
dependence on the temperature and carrier type. At an intermediate temperature
of 600 K, a maximum ZT value of 1.5 and 1.0 can be achieved for the p- and
n-type systems, respectively.
