Hello again Abhinav,

I think that your problem lies in specification of positions. In wurtizite ZnO there are 4 non equivalent positions of Zn and O. in this work: http://cpl.iphy.ac.cn/fileup/PDF/26-1545.pdf you can find the wyckoff positions for ZnO wurtizite:

 Zn (0, 0, 0), (1/3, 2/3, 1/2), O: (0,0,u) and (1/3, 2/3, 1/2+u)

'u' in this case is about 0.345. So IMO you should specify coordinates in following manner:

ATOMIC_POSITIONS crystal

Zn 0.0 0.0 0.0

Zn 0.33333333 0.66666666 0.5

O 0.0 0.0 0.345

O 0.66666666 0.33333333 0.845

Note the 'CRYSTAL'  keyword I;ve used.

Looking in your .in file i have aslo some 'doubts'. First as Zinc is transition metal, the ecutrho should be 8-12 times ecutwfc (if you are using ultrasoft PP). 

Second, I know that when you deal with semiconductor you can use occupations='fixed' but imo use of smearing this case can improve convergence also. 

You should also change the c/a ratio a little and then also try do some more calculations varying a.

Thanks sir.

i am getting a band gap of 7.5 eV when i run ZnO.scf.in and dos.in which were attached

Please let me know where i was doing wrong

thank you

Density of States regarding Zinc Oxide

i am facing the same problem of DOS of ZnO. the energy gap i got of 7.6. i would be thankful if any body can help me.

While plotting DOS on x-axis use E-Ef

Ef -- Fermi energy will be there in scf.out file.

Then proper band gap can be found.