The unit cell of monolayer TMDs CrS 2 and CrSe 2 consist of three atoms: one is transition metal (M = Cr) and another chalcogen (X = S or Se) atoms with MX 2 stoichiometry. These TMDs mainly exhibit three poly-type according to their atomic arrangement, namely, H -phase (hexagonal), T -phase (tetragonal), and T' -phase (distorted). Following the literature , we have chosen H-phase, which is energetically favorable among all these three phases. The hexagonal honeycomb CrX 2 structure consists of one Cr (bonded with 6 nearest X atoms) layer sandwiched between two S or Se atoms such that hexagonal symmetry can be seen from the top view. The X-M-X arrangement along the z-direction is considered a single layer, so-called TMD monolayer. Similarly, the hexagonal Janus CrSSe is formed by replacing one of X (S or Se) atoms layer from the 2H-CrX 2 . In the Janus monolayer CrXY, the transition metal atom is bonded to three X atoms and three Y atoms. They possess reflection asymmetry on Cr-plane which leads to exhibit novel physical and chemical properties.