<html><head><style type='text/css'>p { margin: 0; }</style></head><body><div style='font-family: Times New Roman; font-size: 12pt; color: #000000'><P>Dear Suza</P>
<P> </P>
<P>It seems like BaTiO3 is not a simple cubic structure, so you should not choose ibrav=1.</P>
<P> </P>
<P>Chengyang<BR><BR></P>
<P>
<HR id=zwchr>
</P>
<BLOCKQUOTE style="PADDING-LEFT: 5px; MARGIN-LEFT: 5px; BORDER-LEFT: rgb(16,16,255) 2px solid"><B>From: </B>"Suza W" <suza.rri@gmail.com><BR><B>To: </B>"PWSCF Forum" <pw_forum@pwscf.org><BR><B>Sent: </B>Wednesday, November 30, 2011 3:32:15 PM<BR><B>Subject: </B>[Pw_forum] DC & BEC<BR><BR><BR>Dear All, <BR><BR>Being an epitome of ferroelectric, BaTiO3 has extensively been <BR>studied using PWSCF. However, unfortunately, with several <BR>standard available USPP, I encounter following unphysical results : <BR><BR> Dielectric constant in cartesian axis <BR><BR> (-8142842.391767483 0.000000000 0.000000000 )<BR> ( 0.000000000-8142842.391767481 0.000000000 )<BR> ( 0.000000000 0.000000000-8142842.391767476 )<BR><BR> Effective charges (d Force / dE) in cartesian axis<BR><BR> atom 1 Ba <BR> Ex ( -1136.43937 0.00000 0.00000 )<BR> Ey ( 0.00000 -1136.43937 0.00000 )<BR> Ez ( 0.00000 0.00000 -1136.43937 )<BR> atom 2 Ti <BR> Ex ( -1874.03151 0.00000 0.00000 )<BR> Ey ( 0.00000 -1874.03151 0.00000 )<BR> Ez ( 0.00000 0.00000 -1874.03151 )<BR> atom 3 O <BR> Ex ( 931.42284 0.00000 0.00000 )<BR> Ey ( 0.00000 1067.39482 0.00000 )<BR> Ez ( 0.00000 0.00000 1067.39482 )<BR> atom 4 O <BR> Ex ( 1067.39482 0.00000 0.00000 )<BR> Ey ( 0.00000 931.42284 0.00000 )<BR> Ez ( 0.00000 0.00000 1067.39482 )<BR> atom 5 O <BR> Ex ( 1067.39482 0.00000 0.00000 )<BR> Ey ( 0.00000 1067.39482 0.00000 )<BR> Ez ( 0.00000 0.00000 931.42284 )<BR><BR>Any suggestion for correcting these errors will be highly appreciated. <BR>Here goes the input file which renders such a blunder. <BR> &system<BR> ibrav = 1,<BR> celldm(1) = 7.5589,<BR> nat = 5,<BR> ntyp=3,<BR> ecutwfc = 30.0,<BR> ecutrho = 240.0,<BR> /<BR> &electrons<BR> diagonalization = 'david'<BR> conv_thr = 1.0d-9<BR> mixing_beta = 0.7<BR> /<BR> &ions<BR> /<BR> &cell<BR> /<BR>ATOMIC_SPECIES<BR> Ba 137.327 Ba.pbe-nsp-van.UPF<BR> Ti 47.867 Ti.pbe-sp-van_ak.UPF<BR> O 15.9994 O.pbe-van_ak.UPF<BR>ATOMIC_POSITIONS (alat)<BR>Ba 0.0 0.0 0.0<BR>Ti 0.5 0.5 0.5<BR>O 0.0 0.5 0.5<BR>O 0.5 0.0 0.5<BR>O 0.5 0.5 0.0<BR>K_POINTS {automatic}<BR> 8 8 8 1 1 1<BR><BR>Thanking you, <BR>Yours sincerely, <BR>Suza W<BR>PhD Student <BR>Department of Materials Science<BR>Bangalore<BR><BR>_______________________________________________<BR>Pw_forum mailing list<BR>Pw_forum@pwscf.org<BR>http://www.democritos.it/mailman/listinfo/pw_forum<BR></BLOCKQUOTE><BR></div></body></html>