  Graphdiynes (GDYs) represent a class of 2D carbon materials based on
sp-sp$^2$ hybridization with appealing properties and potential applications.
Recent advances have demonstrated the experimental self-assembly of GDYs on
metal substrates. Here we focus on $\alpha$- and $\beta$-GDYs on Au(111) and
Pt(111), and investigate how their electronic and vibrational properties are
affected by the interaction with a metal substrate. We adopt hydrogenated GDY,
previously characterized experimentally, as a benchmark for density functional
theory simulations, that we apply to show that Au and Pt substrates impose a
different degree of distortion on both $\alpha$- and $\beta$-GDY. By comparing
the adsorbed and the freestanding structures, we evaluate the effect of the
surface interaction on the bandstructure and the simulated Raman spectra.
Different charge transfers result in different energy shift of the Dirac cone
in semi-metallic $\alpha$-GDY and changes from semiconducting to metallic
behavior for $\beta$-GDY. These changes in electronic properties are
accompanied by characteristic frequency shifts and modifications of Raman
active modes. Our results contribute in the understanding of the
metal-interaction effects on GDYs and can open a route to the design of novel
2D materials with tailored properties.
