  In this work, we report an ab initio investigation based on density
functional theory of the structural, energetic and electronic properties of 2D
layered chalcogenides compounds based in the combination of the
transition-metals (Ti, Zr, Hf, V, Nb, Ta, Cr, Mo, W and chalcogenides (S, Se,
Te) in three polymorphic phases: trigonal prismatic (2H), octahedral (1T) and
distorted octahedral (1T$_{\text{d}}$). We determined the most stable phases
for each compound, verifying the existence of the 1T$_{\text{d}}$ phase for a
small number of the compounds and we have also identified the magnetic
compounds. In addition, with the determination of the exfoliation energies, we
indicated the potential candidates to form one layer material and we have also
found a relation between the exfoliation energy and the effective Bader charge
in the metal, suggesting that when the materials present small exfoliation
energy, it is due to the Coulomb repulsion between the chalcogen planes.
Finally, we analyzed the electronic properties, identifying the semiconductor,
semimetal and metal materials and predicting the band gap of the
semiconductors. In our results, the dependence of the band gap on the
$d$-orbital is explicit. In conclusion, we have investigated the properties of
stable and metastable phases for a large set of TMD materials, and our findings
may be auxiliary in the synthesis of metastable phases and in the development
of new TMDs applications.
