<html><head></head><body><div style="font-family:Helvetica Neue;font-size:medium;"><div id="ydp7bfa8da9yiv9697563273"><div><div style="font-family:Helvetica Neue;font-size:medium;"><div id="ydp7bfa8da9yiv9697563273ydpf41b01a9yiv8789745923"><div><div style="font-family:Helvetica Neue;font-size:medium;"><div>Dear all,</div><div><br></div><div><div style="margin-bottom:0in;line-height:100%;" id="ydp7bfa8da9yiv9697563273ydpf41b01a9yiv8789745923ydp34b40c69yiv2549353684yui_3_16_0_1_1496465049175_10361">I am running wien
version 14 on ubuntu 16.<br id="ydp7bfa8da9yiv9697563273ydpf41b01a9yiv8789745923ydp34b40c69yiv2549353684yui_3_16_0_1_1496465049175_10264">
<br id="ydp7bfa8da9yiv9697563273ydpf41b01a9yiv8789745923ydp34b40c69yiv2549353684yui_3_16_0_1_1496465049175_10265">
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<div style="margin-bottom:0in;line-height:100%;" id="ydp7bfa8da9yiv9697563273ydpf41b01a9yiv8789745923ydp34b40c69yiv2549353684yui_3_16_0_1_1496465049175_10266"> The purpose of my
calculations is to calculate the spontaneous polarization for Bi4Ti3O12 tetragonal structure. <br></div></div><div><br></div><div>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. </div><div><br></div><div>Should i make the displacement even more smaller? </div><div><br></div><div>I will be very thankful for any advice.</div><div><br></div><div>Regards</div><div>Jameela Fatheema</div><div>University of Peshawar.<br></div><div><br></div><div><br></div></div></div></div></div></div></div></div></body></html>