**Table 2.**

*Optimization of the diamond structure.*


**Table 3.**

*Valence states, energy, and radius.*

**Figure 3.** *Band structure of diamond.*

512 k-points: 8 8 8 Monkhorst-Pack grid, 60 k-dots in the irreducible part of the Brillouin zone and Coarse grid: 12 12 12 grid as well as the fine grid: 24 24 24 grid. The ordinate axis represents the energy in (eV). It is clear from **Figure 3** that diamond is an insulator with a non-zero band gap since the valence and conduction bands do not meet at the k-point. This corresponds to a zero density of state when plotting the density of state as a function of energy. The band structure is then characterized by a nonlinear dispersion of the bands in the vicinity of the Fermi energy, whereas in graphene, for example, there is a linear dispersion of the bands in the vicinity of the Fermi energy [7].

Next, we calculated the electronic band structure of diamond along the highsymmetry directions in the Brillouin zone [18]. Appendix 1 lists the calculation steps.

First, we performed a standard ground state calculation and saved the results in a . gpw file. As we are dealing with a small bulk system, the plane-wave mode is the most appropriate here.

Next, we calculated the eigenvalues along a high-symmetry path in the Brillouin zone .

See for the definition of the special points for a face-centered cubic (FCC) lattice.

For the band structure calculation, we fixed the density to the previously calculated ground state density, and as we wanted to calculate all k-points, we did not use symmetry ( ).

Finally, we platted the band structure using ASE's band-structure tool ( ):
