POSCAR for slab defined by SURFACE card and Nslab and Vacuum_thickness_in_Angstrom in wt.in by WannierTools
1.0
    3.000000    0.000000    0.000000
    0.000000    3.000000    0.000000
    0.000000    0.000000   22.583544
X     
     4
Cartesian
    0.000000    0.000000    8.141772        X
    0.000000    0.000000   11.141772        X
    0.000000    0.000000   14.141772        X
    0.000000    0.000000   17.141772        X
