Thanks for replying dear Andrei My calculation started with bulk zno( four atoms per unit cell ) .I used lattice parameters and atoms position of experimental data and bandstructure,DOS is ok. Then i made supercell 2*1*2 of the unit cell using wien2k and save it as zno.xsf . its shape using xcrysden was okey. Then for constructing vacuum i increased lattice parameter in x,y,z direction (see the enclosed zno.xsf , super_zno.xsf file). is this procdure is wright for adding vacuum? But surprisingly if you look at the super_zno.xsf you will see that there is a a gap between Zn atoms!!! with no any bonds. What dose this mean and what has happen? Even I have not done any relaxation and calculations?
Best Regards Mahshid
ZnO.xsf
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super_zno.xsf
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