Hi All,
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?? below are my scf.in, nscf.in and polarization part of nscf.out scf.in &CONTROL calculation = 'scf' restart_mode = 'from_scratch' outdir = 'c-kno' , pseudo_dir = '/berry-phase-kno' prefix = 'bp-KNO' / &SYSTEM ibrav=1 celldm(1)=7.59934d0 nat=5 ntyp=3 nbnd=40 ecutwfc=70 occupations = 'fixed' degauss=0.00 / &ELECTRONS conv_thr = 1.D-6, mixing_beta = 0.07 / ATOMIC_SPECIES K 39.09830 K.pz-hgh.UPF Nb 92.90638 Nb.pz-hgh.UPF O 15.99940 O.pz-hgh.UPF ATOMIC_POSITIONS {crystal} K 0.000000000 0.000000000 0.000000000 Nb 0.500000000 0.500000000 0.500000000 O 0.500000000 0.500000000 0.000000000 O 0.500000000 0.000000000 0.500000000 O 0.000000000 0.500000000 0.500000000 K_POINTS {automatic} 4 4 4 0 0 0 nscf.in &CONTROL calculation = 'nscf' restart_mode = 'from_scratch' outdir = 'c-kno' pseudo_dir = '/berry-phase-kno' prefix = 'bp-KNO' lberry = .true. gdir = 3 nppstr = 7 / &SYSTEM ibrav=1 celldm(1)=7.59934d0 nat=5 ntyp=3 nbnd=40 ecutwfc=70 occupations = 'fixed' degauss=0.00 / &ELECTRONS conv_thr = 1.D-6 mixing_beta = 0.07 / ATOMIC_SPECIES K 39.09830 K.pz-hgh.UPF Nb 92.90638 Nb.pz-hgh.UPF O 15.99940 O.pz-hgh.UPF ATOMIC_POSITIONS {crystal} K 0.000000000 0.000000000 0.000000000 Nb 0.500000000 0.500000000 0.500000000 O 0.500000000 0.500000000 0.000000000 O 0.500000000 0.000000000 0.500000000 O 0.000000000 0.500000000 0.500000000 K_POINTS {automatic} 4 4 7 0 0 0 nscf.out VALUES OF POLARIZATION ~~~~~~~~~~~~~~~~~~~~~~ The calculation of phases done along the direction of vector 3 of the reciprocal lattice gives the following contribution to the polarization vector (in different units, and being Omega the volume of the unit cell): P = 3.8195000 (mod 7.6390000) (e/Omega).bohr P = 0.0085683 (mod 0.0171367) e/bohr^2 P = 0.4898671 (mod 0.9797342) C/m^2 The polarization direction is: ( 0.00000 , 0.00000 , 1.00000 ) ================================================== Regards, Rajender Tiwari Ph.D scholar JNU-New Delhi -- Regards, *Rajender Tiwari* *Ph.D. Scholar* *Special Center for Nano Science* *Jawaharlal Nehru University, New Delhi* *#+91-9868970410/ 9873513329* [image: Image result for jnu] Please do not print this email unless it is absolutely necessary. Save the Trees, Save the Earth
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