Heterogeneous monolithic integration of dissimilar materials having different physical properties is today one of the most important challenges for epitaxy scientists. The clarification of wetting properties is one central issue during heterogeneous epitaxy, as it fundamentally governs the growth initiation and physical properties of the integrated materials and devices for photonics, electronics or energy harvesting applications. In this work, we use Density Functional Theory (DFT), with a fictitious hydrogen atoms charge compensation strategy, to determine the surface and interface absolute energies in the III-V/Si heterogeneous materials association case, analyze the wetting properties of III-Vs on Si,[1,2] and discuss the consequences [3,4]. We show that this methodology has been used effectively and could be extended to other heterogeneous materials. On the basis of DFT calculations, we finally demonstrate quantitatively that both the atomic/charge arrangement of the hetero-interface (compensated or not),[5] and the nature of the first monoatomic layer at the substrate surface prior to the growth can dramatically affect the wetting properties. This research was supported by the French National Research NUAGES Project (Grant no. ANR-21-CE24-0006). DFT calculations were performed at FOTON Institute, and the work was granted access to the HPC resources of TGCC/CINES under the allocation A0120911434 made by GENCI. [1] I. Lucci et al., Physical Review Materials 2 (6), 060401 (R), (2018). [2] I. Lucci et al., Advanced Functional Materials, 28(30):1801585, (2018). [3] C. Cornet et al., Phys. Rev. Mater. 4, 053401 (2020). [4] M. Rio Calvo et al., Adv. Electron. Mater. 8, 2100777 (2022). [5] O. Supplie et al., Phys. Rev. B 90, 235301 (2014).