<br clear="all">Dear all,<br><br><span dir="LTR">Trying to calculate the <span class="il">born</span> <span class="il">effective</span> charges of my case, the
obtained diagonalized principal values of effective charge tensor have
imaginary part.</span>
<p class="MsoNormal" style="text-align: left; direction: ltr; unicode-bidi: embed;" align="left">The system has been relaxed carefully using Perdew-Zunger ultrasoft psuedopotentilas by ecutoff=50 (55) Ry, and performing the BZ integration in a 6 grid with 27 reduced<br>
number of k points in the irreducible edge of the 1st BZ.<br><span style=""></span></p><p class="MsoNormal" style="text-align: left; direction: ltr; unicode-bidi: embed;" align="left"><span style="mso-bidi-font-family:Arial">What may cause the problem?</span><span dir="RTL"></span><span dir="RTL" style="font-family:"Arial","sans-serif";
mso-ascii-font-family:Calibri;mso-ascii-theme-font:minor-latin;mso-hansi-font-family:
Calibri;mso-hansi-theme-font:minor-latin" lang="FA"><span dir="RTL"></span></span></p><p class="MsoNormal" style="text-align: left; direction: ltr; unicode-bidi: embed;" align="left"><span style=""><br></span></p><p class="MsoNormal" style="text-align:left;direction:ltr;unicode-bidi:
embed" align="left"><span style="mso-bidi-font-family:Arial">Thanks for any comment</span><span dir="RTL"></span><span dir="RTL" style="font-family:"Arial","sans-serif";
mso-ascii-font-family:Calibri;mso-ascii-theme-font:minor-latin;mso-hansi-font-family:
Calibri;mso-hansi-theme-font:minor-latin" lang="FA"><span dir="RTL"></span>.</span><span style="mso-bidi-font-family:Arial"></span></p>
<br>Yours,<br>M. Abbasnejad<br>University of Tehran<br>