<html><body><div style="color:#000; background-color:#fff; font-family:HelveticaNeue, Helvetica Neue, Helvetica, Arial, Lucida Grande, sans-serif;font-size:12pt"><div><span>Dear Oleg Rubel,</span></div><div style="color: rgb(0, 0, 0); font-size: 16px; font-family: HelveticaNeue,Helvetica Neue,Helvetica,Arial,Lucida Grande,sans-serif; background-color: transparent; font-style: normal;"><br><span></span></div><div style="color: rgb(0, 0, 0); font-size: 16px; font-family: HelveticaNeue,Helvetica Neue,Helvetica,Arial,Lucida Grande,sans-serif; background-color: transparent; font-style: normal;"><span>I have calculated the spontaneous polarization for BiCoO3 in tetragonal structure, and then, <br></span></div><div style="color: rgb(0, 0, 0); font-size: 16px; font-family: HelveticaNeue,Helvetica Neue,Helvetica,Arial,Lucida Grande,sans-serif; background-color: transparent; font-style: normal;"><span>I have got different results between [0 - 2] range and [-1 -
+1] range.</span></div><div style="color: rgb(0, 0, 0); font-size: 16px; font-family: HelveticaNeue,Helvetica Neue,Helvetica,Arial,Lucida Grande,sans-serif; background-color: transparent; font-style: normal;"><span><br></span></div><div style="color: rgb(0, 0, 0); font-size: 16px; font-family: HelveticaNeue,Helvetica Neue,Helvetica,Arial,Lucida Grande,sans-serif; background-color: transparent; font-style: normal;"><span>Please I have some questions:</span></div><div style="color: rgb(0, 0, 0); font-size: 16px; font-family: HelveticaNeue,Helvetica Neue,Helvetica,Arial,Lucida Grande,sans-serif; background-color: transparent; font-style: normal;"><span><br></span></div><div style="color: rgb(0, 0, 0); font-size: 16px; font-family: HelveticaNeue,Helvetica Neue,Helvetica,Arial,Lucida Grande,sans-serif; background-color: transparent; font-style: normal;"><span>- What is the significance of negative values of total polarization ?</span></div><div style="color:
rgb(0, 0, 0); font-size: 16px; font-family: HelveticaNeue,Helvetica Neue,Helvetica,Arial,Lucida Grande,sans-serif; background-color: transparent; font-style: normal;"><span>- Why the values of P_x and P_y is not ~0 ?</span></div><div style="color: rgb(0, 0, 0); font-size: 16px; font-family: HelveticaNeue,Helvetica Neue,Helvetica,Arial,Lucida Grande,sans-serif; background-color: transparent; font-style: normal;"><span>- Is my calculation is true ?</span></div><div style="color: rgb(0, 0, 0); font-size: 16px; font-family: HelveticaNeue,Helvetica Neue,Helvetica,Arial,Lucida Grande,sans-serif; background-color: transparent; font-style: normal;"><span><br></span></div><div style="color: rgb(0, 0, 0); font-size: 16px; font-family: HelveticaNeue,Helvetica Neue,Helvetica,Arial,Lucida Grande,sans-serif; background-color: transparent; font-style: normal;"><span>Please find in attached files the BiCoO3.struct, BiCoO3.berrypi (for non-centrosymmery case)
and </span><br class=""><span>BiCoO3.berrypi (for centrosymmery case).</span></div><div style="color: rgb(0, 0, 0); font-size: 16px; font-family: HelveticaNeue,Helvetica Neue,Helvetica,Arial,Lucida Grande,sans-serif; background-color: transparent; font-style: normal;"><br><span></span></div><div style="color: rgb(0, 0, 0); font-size: 16px; font-family: HelveticaNeue,Helvetica Neue,Helvetica,Arial,Lucida Grande,sans-serif; background-color: transparent; font-style: normal;"><span>NB: the </span><span>spontaneous polarization of BiCoO3 in literature is: 179 uCm/<br></span></div><div><br>Thanks in advance. <br><br></div><div>-------------------------------------------------------<br>Mostefa DJERMOUNI<br>Modeling and Simulation in Materials Science Laboratory<br>University of Sidi Bel-Abbes<br>22000 Sidi Bel-Abbes, Algeria<br>Tel: +213 795 626 105<br>-------------------------------------------------------</div></div></body></html>