<div dir="ltr">

<span style="font-size:12.8px;text-decoration-style:initial;text-decoration-color:initial;float:none;display:inline">Hi All,</span><br style="font-size:12.8px;text-decoration-style:initial;text-decoration-color:initial"><div style="font-size:12.8px;text-decoration-style:initial;text-decoration-color:initial"><br></div><div style="font-size:12.8px;text-decoration-style:initial;text-decoration-color:initial"><br></div><span style="font-size:12.8px;text-decoration-style:initial;text-decoration-color:initial;float:none;display:inline">I'm calculating berry phase polarization in KNbO3(KNO).  Ideally, for a perfect cubic KNO the polarization should be zero. However, I’m getting 0.4898671 C/m^2. I’ve no idea why am I getting this result. Can anyone help??</span><br style="font-size:12.8px;text-decoration-style:initial;text-decoration-color:initial"><span style="font-size:12.8px;text-decoration-style:initial;text-decoration-color:initial;float:none;display:inline">below are my<span> </span></span><a href="http://scf.in/" target="_blank" style="color:rgb(17,85,204);font-size:12.8px">scf.in</a><span style="font-size:12.8px;text-decoration-style:initial;text-decoration-color:initial;float:none;display:inline">,<span> </span></span><a href="http://nscf.in/" target="_blank" style="color:rgb(17,85,204);font-size:12.8px">nscf.in</a><span style="font-size:12.8px;text-decoration-style:initial;text-decoration-color:initial;float:none;display:inline"><span> </span>and polarization part of nscf.out<span> </span></span><br style="font-size:12.8px;text-decoration-style:initial;text-decoration-color:initial"><br style="font-size:12.8px;text-decoration-style:initial;text-decoration-color:initial"><div style="font-size:12.8px;text-decoration-style:initial;text-decoration-color:initial"><a href="http://scf.in/" target="_blank" style="color:rgb(17,85,204)">scf.in</a></div><div style="font-size:12.8px;text-decoration-style:initial;text-decoration-color:initial"><br></div><span style="font-size:12.8px;text-decoration-style:initial;text-decoration-color:initial;float:none;display:inline">&CONTROL</span><br style="font-size:12.8px;text-decoration-style:initial;text-decoration-color:initial"><span style="font-size:12.8px;text-decoration-style:initial;text-decoration-color:initial;float:none;display:inline">    calculation = 'scf'</span><br style="font-size:12.8px;text-decoration-style:initial;text-decoration-color:initial"><span style="font-size:12.8px;text-decoration-style:initial;text-decoration-color:initial;float:none;display:inline">    restart_mode = 'from_scratch'<span> </span></span><br style="font-size:12.8px;text-decoration-style:initial;text-decoration-color:initial"><span style="font-size:12.8px;text-decoration-style:initial;text-decoration-color:initial;float:none;display:inline">    outdir = 'c-kno' ,</span><br style="font-size:12.8px;text-decoration-style:initial;text-decoration-color:initial"><span style="font-size:12.8px;text-decoration-style:initial;text-decoration-color:initial;float:none;display:inline">    pseudo_dir = '/berry-phase-kno'</span><br style="font-size:12.8px;text-decoration-style:initial;text-decoration-color:initial"><span style="font-size:12.8px;text-decoration-style:initial;text-decoration-color:initial;float:none;display:inline">    prefix = 'bp-KNO'</span><br style="font-size:12.8px;text-decoration-style:initial;text-decoration-color:initial"><span style="font-size:12.8px;text-decoration-style:initial;text-decoration-color:initial;float:none;display:inline">/</span><br style="font-size:12.8px;text-decoration-style:initial;text-decoration-color:initial"><br style="font-size:12.8px;text-decoration-style:initial;text-decoration-color:initial"><span style="font-size:12.8px;text-decoration-style:initial;text-decoration-color:initial;float:none;display:inline">&SYSTEM</span><br style="font-size:12.8px;text-decoration-style:initial;text-decoration-color:initial"><span style="font-size:12.8px;text-decoration-style:initial;text-decoration-color:initial;float:none;display:inline">    ibrav=1</span><br style="font-size:12.8px;text-decoration-style:initial;text-decoration-color:initial"><span style="font-size:12.8px;text-decoration-style:initial;text-decoration-color:initial;float:none;display:inline">    celldm(1)=7.59934d0</span><br style="font-size:12.8px;text-decoration-style:initial;text-decoration-color:initial"><span style="font-size:12.8px;text-decoration-style:initial;text-decoration-color:initial;float:none;display:inline">    nat=5</span><br style="font-size:12.8px;text-decoration-style:initial;text-decoration-color:initial"><span style="font-size:12.8px;text-decoration-style:initial;text-decoration-color:initial;float:none;display:inline">    ntyp=3</span><br style="font-size:12.8px;text-decoration-style:initial;text-decoration-color:initial"><span style="font-size:12.8px;text-decoration-style:initial;text-decoration-color:initial;float:none;display:inline">    nbnd=40</span><br style="font-size:12.8px;text-decoration-style:initial;text-decoration-color:initial"><span style="font-size:12.8px;text-decoration-style:initial;text-decoration-color:initial;float:none;display:inline">    ecutwfc=70</span><br style="font-size:12.8px;text-decoration-style:initial;text-decoration-color:initial"><span style="font-size:12.8px;text-decoration-style:initial;text-decoration-color:initial;float:none;display:inline">    occupations = 'fixed'</span><br style="font-size:12.8px;text-decoration-style:initial;text-decoration-color:initial"><span style="font-size:12.8px;text-decoration-style:initial;text-decoration-color:initial;float:none;display:inline">    degauss=0.00</span><br style="font-size:12.8px;text-decoration-style:initial;text-decoration-color:initial"><br style="font-size:12.8px;text-decoration-style:initial;text-decoration-color:initial"><span style="font-size:12.8px;text-decoration-style:initial;text-decoration-color:initial;float:none;display:inline">/</span><br style="font-size:12.8px;text-decoration-style:initial;text-decoration-color:initial"><br style="font-size:12.8px;text-decoration-style:initial;text-decoration-color:initial"><span style="font-size:12.8px;text-decoration-style:initial;text-decoration-color:initial;float:none;display:inline">&ELECTRONS</span><br style="font-size:12.8px;text-decoration-style:initial;text-decoration-color:initial"><span style="font-size:12.8px;text-decoration-style:initial;text-decoration-color:initial;float:none;display:inline">    conv_thr    = 1.D-6,</span><br style="font-size:12.8px;text-decoration-style:initial;text-decoration-color:initial"><span style="font-size:12.8px;text-decoration-style:initial;text-decoration-color:initial;float:none;display:inline">    mixing_beta = 0.07</span><br style="font-size:12.8px;text-decoration-style:initial;text-decoration-color:initial"><span style="font-size:12.8px;text-decoration-style:initial;text-decoration-color:initial;float:none;display:inline">/</span><br style="font-size:12.8px;text-decoration-style:initial;text-decoration-color:initial"><br style="font-size:12.8px;text-decoration-style:initial;text-decoration-color:initial"><span style="font-size:12.8px;text-decoration-style:initial;text-decoration-color:initial;float:none;display:inline">ATOMIC_SPECIES</span><br style="font-size:12.8px;text-decoration-style:initial;text-decoration-color:initial"><span style="font-size:12.8px;text-decoration-style:initial;text-decoration-color:initial;float:none;display:inline">    K 39.09830 K.pz-hgh.UPF</span><br style="font-size:12.8px;text-decoration-style:initial;text-decoration-color:initial"><span style="font-size:12.8px;text-decoration-style:initial;text-decoration-color:initial;float:none;display:inline">    Nb 92.90638 Nb.pz-hgh.UPF   <span> </span></span><br style="font-size:12.8px;text-decoration-style:initial;text-decoration-color:initial"><span style="font-size:12.8px;text-decoration-style:initial;text-decoration-color:initial;float:none;display:inline">    O 15.99940 O.pz-hgh.UPF   <span> </span></span><br style="font-size:12.8px;text-decoration-style:initial;text-decoration-color:initial"><br style="font-size:12.8px;text-decoration-style:initial;text-decoration-color:initial"><span style="font-size:12.8px;text-decoration-style:initial;text-decoration-color:initial;float:none;display:inline">ATOMIC_POSITIONS {crystal}</span><br style="font-size:12.8px;text-decoration-style:initial;text-decoration-color:initial"><span style="font-size:12.8px;text-decoration-style:initial;text-decoration-color:initial;float:none;display:inline">K        0.000000000   0.000000000   0.000000000</span><br style="font-size:12.8px;text-decoration-style:initial;text-decoration-color:initial"><span style="font-size:12.8px;text-decoration-style:initial;text-decoration-color:initial;float:none;display:inline">Nb      0.500000000   0.500000000   0.500000000</span><br style="font-size:12.8px;text-decoration-style:initial;text-decoration-color:initial"><span style="font-size:12.8px;text-decoration-style:initial;text-decoration-color:initial;float:none;display:inline">O        0.500000000   0.500000000   0.000000000</span><br style="font-size:12.8px;text-decoration-style:initial;text-decoration-color:initial"><span style="font-size:12.8px;text-decoration-style:initial;text-decoration-color:initial;float:none;display:inline">O        0.500000000   0.000000000   0.500000000</span><br style="font-size:12.8px;text-decoration-style:initial;text-decoration-color:initial"><span style="font-size:12.8px;text-decoration-style:initial;text-decoration-color:initial;float:none;display:inline">O        0.000000000   0.500000000   0.500000000</span><br style="font-size:12.8px;text-decoration-style:initial;text-decoration-color:initial"><br style="font-size:12.8px;text-decoration-style:initial;text-decoration-color:initial"><span style="font-size:12.8px;text-decoration-style:initial;text-decoration-color:initial;float:none;display:inline">K_POINTS {automatic}<span> </span></span><br style="font-size:12.8px;text-decoration-style:initial;text-decoration-color:initial"><span style="font-size:12.8px;text-decoration-style:initial;text-decoration-color:initial;float:none;display:inline">4 4 4  0 0 0</span><br style="font-size:12.8px;text-decoration-style:initial;text-decoration-color:initial"><br style="font-size:12.8px;text-decoration-style:initial;text-decoration-color:initial"><br style="font-size:12.8px;text-decoration-style:initial;text-decoration-color:initial"><br style="font-size:12.8px;text-decoration-style:initial;text-decoration-color:initial"><br style="font-size:12.8px;text-decoration-style:initial;text-decoration-color:initial"><br style="font-size:12.8px;text-decoration-style:initial;text-decoration-color:initial"><a href="http://nscf.in/" target="_blank" style="color:rgb(17,85,204);font-size:12.8px">nscf.in</a><br style="font-size:12.8px;text-decoration-style:initial;text-decoration-color:initial"><br style="font-size:12.8px;text-decoration-style:initial;text-decoration-color:initial"><span style="font-size:12.8px;text-decoration-style:initial;text-decoration-color:initial;float:none;display:inline">&CONTROL</span><br style="font-size:12.8px;text-decoration-style:initial;text-decoration-color:initial"><span style="font-size:12.8px;text-decoration-style:initial;text-decoration-color:initial;float:none;display:inline">    calculation = 'nscf'</span><br style="font-size:12.8px;text-decoration-style:initial;text-decoration-color:initial"><span style="font-size:12.8px;text-decoration-style:initial;text-decoration-color:initial;float:none;display:inline">    restart_mode = 'from_scratch'<span> </span></span><br style="font-size:12.8px;text-decoration-style:initial;text-decoration-color:initial"><span style="font-size:12.8px;text-decoration-style:initial;text-decoration-color:initial;float:none;display:inline">    outdir = 'c-kno'<span> </span></span><br style="font-size:12.8px;text-decoration-style:initial;text-decoration-color:initial"><span style="font-size:12.8px;text-decoration-style:initial;text-decoration-color:initial;float:none;display:inline">    pseudo_dir = '/berry-phase-kno'</span><br style="font-size:12.8px;text-decoration-style:initial;text-decoration-color:initial"><span style="font-size:12.8px;text-decoration-style:initial;text-decoration-color:initial;float:none;display:inline">    prefix = 'bp-KNO'</span><br style="font-size:12.8px;text-decoration-style:initial;text-decoration-color:initial"><span style="font-size:12.8px;text-decoration-style:initial;text-decoration-color:initial;float:none;display:inline">    lberry = .true.</span><br style="font-size:12.8px;text-decoration-style:initial;text-decoration-color:initial"><span style="font-size:12.8px;text-decoration-style:initial;text-decoration-color:initial;float:none;display:inline">    gdir = 3</span><br style="font-size:12.8px;text-decoration-style:initial;text-decoration-color:initial"><span style="font-size:12.8px;text-decoration-style:initial;text-decoration-color:initial;float:none;display:inline">    nppstr = 7</span><br style="font-size:12.8px;text-decoration-style:initial;text-decoration-color:initial"><span style="font-size:12.8px;text-decoration-style:initial;text-decoration-color:initial;float:none;display:inline">/</span><br style="font-size:12.8px;text-decoration-style:initial;text-decoration-color:initial"><br style="font-size:12.8px;text-decoration-style:initial;text-decoration-color:initial"><span style="font-size:12.8px;text-decoration-style:initial;text-decoration-color:initial;float:none;display:inline">&SYSTEM</span><br style="font-size:12.8px;text-decoration-style:initial;text-decoration-color:initial"><span style="font-size:12.8px;text-decoration-style:initial;text-decoration-color:initial;float:none;display:inline">    ibrav=1</span><br style="font-size:12.8px;text-decoration-style:initial;text-decoration-color:initial"><span style="font-size:12.8px;text-decoration-style:initial;text-decoration-color:initial;float:none;display:inline">    celldm(1)=7.59934d0</span><br style="font-size:12.8px;text-decoration-style:initial;text-decoration-color:initial"><span style="font-size:12.8px;text-decoration-style:initial;text-decoration-color:initial;float:none;display:inline">    nat=5</span><br style="font-size:12.8px;text-decoration-style:initial;text-decoration-color:initial"><span style="font-size:12.8px;text-decoration-style:initial;text-decoration-color:initial;float:none;display:inline">    ntyp=3</span><br style="font-size:12.8px;text-decoration-style:initial;text-decoration-color:initial"><span style="font-size:12.8px;text-decoration-style:initial;text-decoration-color:initial;float:none;display:inline">    nbnd=40</span><br style="font-size:12.8px;text-decoration-style:initial;text-decoration-color:initial"><span style="font-size:12.8px;text-decoration-style:initial;text-decoration-color:initial;float:none;display:inline">    ecutwfc=70</span><br style="font-size:12.8px;text-decoration-style:initial;text-decoration-color:initial"><span style="font-size:12.8px;text-decoration-style:initial;text-decoration-color:initial;float:none;display:inline">    occupations = 'fixed'</span><br style="font-size:12.8px;text-decoration-style:initial;text-decoration-color:initial"><span style="font-size:12.8px;text-decoration-style:initial;text-decoration-color:initial;float:none;display:inline">    degauss=0.00</span><br style="font-size:12.8px;text-decoration-style:initial;text-decoration-color:initial"><br style="font-size:12.8px;text-decoration-style:initial;text-decoration-color:initial"><span style="font-size:12.8px;text-decoration-style:initial;text-decoration-color:initial;float:none;display:inline">/</span><br style="font-size:12.8px;text-decoration-style:initial;text-decoration-color:initial"><br style="font-size:12.8px;text-decoration-style:initial;text-decoration-color:initial"><span style="font-size:12.8px;text-decoration-style:initial;text-decoration-color:initial;float:none;display:inline">&ELECTRONS</span><br style="font-size:12.8px;text-decoration-style:initial;text-decoration-color:initial"><span style="font-size:12.8px;text-decoration-style:initial;text-decoration-color:initial;float:none;display:inline">    conv_thr    = 1.D-6</span><br style="font-size:12.8px;text-decoration-style:initial;text-decoration-color:initial"><span style="font-size:12.8px;text-decoration-style:initial;text-decoration-color:initial;float:none;display:inline">    mixing_beta = 0.07</span><br style="font-size:12.8px;text-decoration-style:initial;text-decoration-color:initial"><span style="font-size:12.8px;text-decoration-style:initial;text-decoration-color:initial;float:none;display:inline">/</span><br style="font-size:12.8px;text-decoration-style:initial;text-decoration-color:initial"><br style="font-size:12.8px;text-decoration-style:initial;text-decoration-color:initial"><span style="font-size:12.8px;text-decoration-style:initial;text-decoration-color:initial;float:none;display:inline">ATOMIC_SPECIES</span><br style="font-size:12.8px;text-decoration-style:initial;text-decoration-color:initial"><span style="font-size:12.8px;text-decoration-style:initial;text-decoration-color:initial;float:none;display:inline">    K 39.09830 K.pz-hgh.UPF</span><br style="font-size:12.8px;text-decoration-style:initial;text-decoration-color:initial"><span style="font-size:12.8px;text-decoration-style:initial;text-decoration-color:initial;float:none;display:inline">    Nb 92.90638 Nb.pz-hgh.UPF   <span> </span></span><br style="font-size:12.8px;text-decoration-style:initial;text-decoration-color:initial"><span style="font-size:12.8px;text-decoration-style:initial;text-decoration-color:initial;float:none;display:inline">    O 15.99940 O.pz-hgh.UPF   <span> </span></span><br style="font-size:12.8px;text-decoration-style:initial;text-decoration-color:initial"><br style="font-size:12.8px;text-decoration-style:initial;text-decoration-color:initial"><span style="font-size:12.8px;text-decoration-style:initial;text-decoration-color:initial;float:none;display:inline">ATOMIC_POSITIONS {crystal}</span><br style="font-size:12.8px;text-decoration-style:initial;text-decoration-color:initial"><span style="font-size:12.8px;text-decoration-style:initial;text-decoration-color:initial;float:none;display:inline">K        0.000000000   0.000000000   0.000000000</span><br style="font-size:12.8px;text-decoration-style:initial;text-decoration-color:initial"><span style="font-size:12.8px;text-decoration-style:initial;text-decoration-color:initial;float:none;display:inline">Nb      0.500000000   0.500000000   0.500000000</span><br style="font-size:12.8px;text-decoration-style:initial;text-decoration-color:initial"><span style="font-size:12.8px;text-decoration-style:initial;text-decoration-color:initial;float:none;display:inline">O        0.500000000   0.500000000   0.000000000</span><br style="font-size:12.8px;text-decoration-style:initial;text-decoration-color:initial"><span style="font-size:12.8px;text-decoration-style:initial;text-decoration-color:initial;float:none;display:inline">O        0.500000000   0.000000000   0.500000000</span><br style="font-size:12.8px;text-decoration-style:initial;text-decoration-color:initial"><span style="font-size:12.8px;text-decoration-style:initial;text-decoration-color:initial;float:none;display:inline">O        0.000000000   0.500000000   0.500000000</span><br style="font-size:12.8px;text-decoration-style:initial;text-decoration-color:initial"><br style="font-size:12.8px;text-decoration-style:initial;text-decoration-color:initial"><span style="font-size:12.8px;text-decoration-style:initial;text-decoration-color:initial;float:none;display:inline">K_POINTS {automatic}<span> </span></span><br style="font-size:12.8px;text-decoration-style:initial;text-decoration-color:initial"><span style="font-size:12.8px;text-decoration-style:initial;text-decoration-color:initial;float:none;display:inline">4 4 7  0 0 0</span><br style="font-size:12.8px;text-decoration-style:initial;text-decoration-color:initial"><br style="font-size:12.8px;text-decoration-style:initial;text-decoration-color:initial"><br style="font-size:12.8px;text-decoration-style:initial;text-decoration-color:initial"><br style="font-size:12.8px;text-decoration-style:initial;text-decoration-color:initial"><br style="font-size:12.8px;text-decoration-style:initial;text-decoration-color:initial"><br style="font-size:12.8px;text-decoration-style:initial;text-decoration-color:initial"><br style="font-size:12.8px;text-decoration-style:initial;text-decoration-color:initial"><br style="font-size:12.8px;text-decoration-style:initial;text-decoration-color:initial"><span style="font-size:12.8px;text-decoration-style:initial;text-decoration-color:initial;float:none;display:inline">nscf.out</span><br style="font-size:12.8px;text-decoration-style:initial;text-decoration-color:initial"><br style="font-size:12.8px;text-decoration-style:initial;text-decoration-color:initial"><br style="font-size:12.8px;text-decoration-style:initial;text-decoration-color:initial"><span style="font-size:12.8px;text-decoration-style:initial;text-decoration-color:initial;float:none;display:inline">                             VALUES OF POLARIZATION</span><br style="font-size:12.8px;text-decoration-style:initial;text-decoration-color:initial"><span style="font-size:12.8px;text-decoration-style:initial;text-decoration-color:initial;float:none;display:inline">                             ~~~~~~~~~~~~~~~~~~~~~~</span><br style="font-size:12.8px;text-decoration-style:initial;text-decoration-color:initial"><br style="font-size:12.8px;text-decoration-style:initial;text-decoration-color:initial"><span style="font-size:12.8px;text-decoration-style:initial;text-decoration-color:initial;float:none;display:inline">        The calculation of phases done along the direction of vector 3</span><br style="font-size:12.8px;text-decoration-style:initial;text-decoration-color:initial"><span style="font-size:12.8px;text-decoration-style:initial;text-decoration-color:initial;float:none;display:inline">        of the reciprocal lattice gives the following contribution to</span><br style="font-size:12.8px;text-decoration-style:initial;text-decoration-color:initial"><span style="font-size:12.8px;text-decoration-style:initial;text-decoration-color:initial;float:none;display:inline">        the polarization vector (in different units, and being Omega</span><br style="font-size:12.8px;text-decoration-style:initial;text-decoration-color:initial"><span style="font-size:12.8px;text-decoration-style:initial;text-decoration-color:initial;float:none;display:inline">        the volume of the unit cell):</span><br style="font-size:12.8px;text-decoration-style:initial;text-decoration-color:initial"><br style="font-size:12.8px;text-decoration-style:initial;text-decoration-color:initial"><span style="font-size:12.8px;text-decoration-style:initial;text-decoration-color:initial;float:none;display:inline">           P =   3.8195000  (mod   7.6390000)  (e/Omega).bohr</span><br style="font-size:12.8px;text-decoration-style:initial;text-decoration-color:initial"><br style="font-size:12.8px;text-decoration-style:initial;text-decoration-color:initial"><span style="font-size:12.8px;text-decoration-style:initial;text-decoration-color:initial;float:none;display:inline">           P =   0.0085683  (mod   0.0171367)  e/bohr^2</span><br style="font-size:12.8px;text-decoration-style:initial;text-decoration-color:initial"><br style="font-size:12.8px;text-decoration-style:initial;text-decoration-color:initial"><span style="font-size:12.8px;text-decoration-style:initial;text-decoration-color:initial;float:none;display:inline">           P =   0.4898671  (mod   0.9797342)  C/m^2</span><br style="font-size:12.8px;text-decoration-style:initial;text-decoration-color:initial"><br style="font-size:12.8px;text-decoration-style:initial;text-decoration-color:initial"><span style="font-size:12.8px;text-decoration-style:initial;text-decoration-color:initial;float:none;display:inline">        The polarization direction is:  ( 0.00000 , 0.00000 , 1.00000 )</span><br style="font-size:12.8px;text-decoration-style:initial;text-decoration-color:initial"><br style="font-size:12.8px;text-decoration-style:initial;text-decoration-color:initial"><br style="font-size:12.8px;text-decoration-style:initial;text-decoration-color:initial"><span style="font-size:12.8px;text-decoration-style:initial;text-decoration-color:initial;float:none;display:inline">               ==============================</span><wbr style="font-size:12.8px;text-decoration-style:initial;text-decoration-color:initial"><span style="font-size:12.8px;text-decoration-style:initial;text-decoration-color:initial;float:none;display:inline">====================</span>

<br><div><br></div><div>Regards,</div><div>Rajender Tiwari</div><div>Ph.D scholar</div><div>JNU-New Delhi</div></div>