[Wien] symmetry problem for spontaneous polarization

[Jameela Fatheema]

Dear all,
I am running wienversion 14 on ubuntu 16.

 The purpose of mycalculations is to calculate the spontaneous polarization for Bi4Ti3O12 tetragonal structure. 

I have followed the steps provided by the wien2k UG and the notes that are available on wien2k site. The space group is I4/mmm which genertaes 16 symmetry operations for the structure. For the noncentrosymmetric polarization, i displace the titanium and oxygen atoms in the z-direction, about 0.005. this changes the symmetry to 8 and i get the space group as I4mm. After the total polarization for I4mm is obtained i do the steps as mentioned in the notes and tutorial available. The problem is how do i avoid this symmetry change because as much i understand the symmetry needs to remain the same. If i dont do the initialization for the centrosyymetric calculations it shows the ROTDEF error in dstart which is due to the symmetry difference. 
Should i make the displacement even more smaller? 
I will be very thankful for any advice.
RegardsJameela FatheemaUniversity of Peshawar.


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