Hello,

I am doing DFT analysis of bulk, bilayer and monolayer of TiS2 (following this video https://www.youtube.com/watch?v=2buVIKiThPM) in MS-CASTEP, please see the Fig. 1 and got some interesting results, for example see Fig. 2 of the BandStructure. 

Please suggest if my concept of bulk, bilayer and monolayer of TiS2 in Fig. 1 is correct? If it is correct then why the band gap changes when I change the vacuum level in the bilayer and monolayer of TiO2?