<html><body><div style="color:#000; background-color:#fff; font-family:HelveticaNeue, Helvetica Neue, Helvetica, Arial, Lucida Grande, Sans-Serif;font-size:14pt"><div>Dear authors of Nature Communications | DOI: 10.1038/ncomms3511,</div><div class="yiv3559011029gmail_default"><span style="font-size: 19px; border-collapse: collapse;"></span><div style='font-family: HelveticaNeue, "Helvetica Neue", Helvetica, Arial, "Lucida Grande", sans-serif;'> <span style="line-height: 21px; font-family: Helvetica, sans-serif; font-size: 14pt;"><span><br clear="none"></span></span></div><div style='font-family: HelveticaNeue, "Helvetica Neue", Helvetica, Arial, "Lucida Grande", sans-serif;'><span style="line-height: 21px; font-family: Helvetica, sans-serif; font-size: 14pt;"><span>I have an inquiry concerning the Spin-Orbit (SP) coupling in calculating of the electronic polarization within the WIEN2k code using the Berry Phase approach for CuO. In the paper, it is
indicated that "To have adequate electric polarization values, it was crucial to turn on the SO coupling during the structural relaxation." </span></span></div><span style="font-size: 19px; border-collapse: collapse;"></span><div style='font-family: HelveticaNeue, "Helvetica Neue", Helvetica, Arial, "Lucida Grande", sans-serif;'><span style="line-height: 21px; font-family: Helvetica, sans-serif; font-size: 14pt;"><span><br clear="none"></span></span></div><div style='font-family: HelveticaNeue, "Helvetica Neue", Helvetica, Arial, "Lucida Grande", sans-serif;'><span style="line-height: 21px; font-family: Helvetica, sans-serif; font-size: 14pt;"><span>As far as I know SO has been very recently implemented in the BerryPI code by Oleg Rubel (after publishing the Nature Commun.) . I am not sure whether the BerryPI developed by Oleg was used in the above paper. Maybe you had your own developed unofficial Berry Phase program with
SO(?).</span></span></div><span style="line-height: 21px; font-family: Helvetica, sans-serif; font-size: 19px; border-collapse: collapse;"></span><div class="yiv3559011029gmail_default"><span style="line-height: 21px; font-family: Helvetica, sans-serif; font-size: 19px; border-collapse: collapse;"><br clear="none"></span></div>So, my question is that whether the SO coupling was used only for relaxation of the system or it was applied for calculating the electronic polarization too.<span style="line-height: 21px; font-family: Helvetica, sans-serif; font-size: 19px; border-collapse: collapse;"> </span><span style="font-size: 19px; border-collapse: collapse;"></span><div style='font-family: HelveticaNeue, "Helvetica Neue", Helvetica, Arial, "Lucida Grande", sans-serif;'> <span style="line-height: 21px; font-family: Helvetica, sans-serif; font-size: 14pt;"><span><br clear="none"></span></span></div><div style='font-family: HelveticaNeue, "Helvetica
Neue", Helvetica, Arial, "Lucida Grande", sans-serif;'><span style="line-height: 21px; font-family: Helvetica, sans-serif; font-size: 14pt;"><span>Thank you for your attention to this matter.</span></span></div><span style="line-height: 21px; font-family: Helvetica, sans-serif; font-size: 19px; border-collapse: collapse;"></span><div class="yiv3559011029gmail_default" style="font-size: large;"> <span style="line-height: 21px; font-family: Helvetica, sans-serif; font-size: 19px; border-collapse: collapse;"><br clear="none"></span></div>Best regards,<span style="font-size: 19px; border-collapse: collapse;"></span><span style="line-height: 21px; font-family: Helvetica, sans-serif; font-size: 19px; border-collapse: collapse;"> </span></div><div class="yiv3559011029gmail_default" style="font-size: large;"><span style="line-height: 21px; font-family: Helvetica, sans-serif; font-size: 19px; border-collapse: collapse;">SH. Rahimi</span><span
style="font-size: 19px; border-collapse: collapse;"></span><div style='font-family: HelveticaNeue, "Helvetica Neue", Helvetica, Arial, "Lucida Grande", sans-serif;'> <span style="line-height: 21px; font-family: Helvetica, sans-serif; font-size: 14pt;"><span>Graduate Student at University of Isfahan </span></span></div></div></div></body></html>