Using density functional theory with semiempirical and analytical corrections for dispersion, a model of the g-CN/graphene bilayer was studied. Calculations were performed using two different approaches to wave function decomposition implemented in software packages VASP and SIESTA. It is found that to obtain optimal parameters for the atomic-like basis in SIESTA package, it is sufficient to independently optimize the orbitals using the standard exchange-correlation functional. It is also shown that to obtain accurate energetic and structural characteristics of the g-CN/graphene bilayer, it is necessary to use a sufficiently large atomic-like basis set, optimize its parameters, and apply corrections to the basis set superposition error in both the interlayer binding energy and interlayer distance calculations. Otherwise, the binding energy may be significantly overestimated (up to seven to eight times in some cases), and the interlayer distance may be underestimated by 4–15%. The final binding energy was about 50 meV per graphene atom, indicating weak van der Waals interactions between the CN and graphene monolayers. The obtained density of states diagrams showed that using a CN monolayer, as a substrate for graphene did not lead to the opening of a bandgap in it.
Anikina et al. (Wed,) studied this question.