Thank you very much for your reply Andrei. On Fri, Feb 20, 2015 at 10:45 AM, Andrei Malashevich < [email protected]> wrote:
> Dear Javier, > > For spin-polarized case, you have 0.6698526-1.0038673=-0.3340147, > value very similar to the spin unpolarized case. > Polarization is defined only modulo a quantum, and in the above, I just > subtracted the quantum. > > Andrei > > > On Fri, Feb 20, 2015 at 10:27 AM, Nossa, Javier < > [email protected]> wrote: > >> Dear pwscfers, >> I am calculating the polarization of BaTiO3 and found a different value >> of it when implementing spin-polarized, nspin=2. >> >> non-spin-polarized gives P=-0.3340199 (mod 2.0077346) C/m^2, which is >> correct. >> spin-polarized gives P=0.6698526 (mod 1.0038673) C/m^2, which is not >> correct. >> >> Although it seems to be just a factor of two difference in the absolute >> value of the polarization, it is not exactly a factor of two. It is >> 2.0054... >> In addition, the sign of the polarization is opposite. >> On the other hand, the mod is exactly a factor of two. >> >> Why there is such a difference in the polarization? >> >> I am doing this as a test because my real system is magnetic and bigger >> than BaTiO3. >> >> Here are the inputs for the nscf calculation: >> >> spin-polarized: >> &control >> calculation='nscf' >> restart_mode='from_scratch', >> prefix='job', >> lberry = .true. >> gdir = 3 >> nppstr = 10 >> / >> &system >> ibrav= 0, >> celldm(1)=1.0, >> nat= 5, ntyp= 3, >> ecutwfc = 120, >> !occupations='smearing', smearing='gauss', degauss=0.003, >> !occupations='fixed', >> input_dft='wc' >> nspin=2, >> tot_magnetization= 0.0, >> / >> &electrons >> / >> ATOMIC_SPECIES >> Ba 137.327 Ba.wc-n-nc.UPF >> Ti 47.867 Ti.wc-n-nc.UPF >> O 15.9994 O.wc-nc.UPF >> CELL_PARAMETERS (alat=1.0) >> 7.54662 0.0 0.0 >> 0.0 7.54662 0.0 >> 0.0 0.0 7.74409 >> ATOMIC_POSITIONS {crystal} >> Ba 0.00000 0.00000 0.00000 >> Ti 0.50000 0.50000 0.48186 >> O 0.00000 0.50000 0.51791 >> O 0.50000 0.00000 0.51791 >> O 0.50000 0.50000 0.03133 >> K_POINTS {automatic} >> 4 4 4 0 0 0 >> >> >> non-spin-polarized: >> &control >> calculation='nscf' >> restart_mode='from_scratch', >> prefix='job', >> lberry = .true. >> gdir = 3 >> nppstr = 10 >> / >> &system >> ibrav= 0, >> celldm(1)=1.0, >> nat= 5, ntyp= 3, >> ecutwfc = 120, >> !occupations='smearing', smearing='gauss', degauss=0.003, >> !occupations='fixed', >> input_dft='wc' >> / >> &electrons >> / >> ATOMIC_SPECIES >> Ba 137.327 Ba.wc-n-nc.UPF >> Ti 47.867 Ti.wc-n-nc.UPF >> O 15.9994 O.wc-nc.UPF >> CELL_PARAMETERS (alat=1.0) >> 7.54662 0.0 0.0 >> 0.0 7.54662 0.0 >> 0.0 0.0 7.74409 >> ATOMIC_POSITIONS {crystal} >> Ba 0.00000 0.00000 0.00000 >> Ti 0.50000 0.50000 0.48186 >> O 0.00000 0.50000 0.51791 >> O 0.50000 0.00000 0.51791 >> O 0.50000 0.50000 0.03133 >> K_POINTS {automatic} >> 4 4 4 0 0 0 >> >> >> Pseudopotentials are taken from THEOS PSLibrary 0.3.1. >> >> Outputs are attached. >> >> >> Thank you very much for your help. >> >> -- >> With best regards, >> Javier Francisco Nossa >> >> Postdoc at Geophysical Laboratory >> Carnegie Institution of Washington >> 5251 Broad Branch Road, N.W. >> Washington, DC 20015-1305 >> Tel.: 1.240.476.3993 >> E-mail: [email protected] <[email protected]> >> >> _______________________________________________ >> Pw_forum mailing list >> [email protected] >> >> https://urldefense.proofpoint.com/v2/url?u=http-3A__pwscf.org_mailman_listinfo_pw-5Fforum&d=AwICAg&c=-dg2m7zWuuDZ0MUcV7Sdqw&r=iaCUSkNPjaS0OZmx8CL3zuFJHmomB6kEDsD3Du2Xz38&m=jHc1e4BMDezKEN4w-4Sz3WYY43oEOCVzdofkatuhMr0&s=ptunJ7qbTZCjdsr3TWNH3-Yh3KVY76v7PTd5Aj-blsQ&e= >> > > > > -- > Andrei Malashevich > Postdoctoral Associate > Center for Research on Interface Structures and Phenomena > Department of Applied Physics > Yale University > > _______________________________________________ > Pw_forum mailing list > [email protected] > http://pwscf.org/mailman/listinfo/pw_forum > -- With best regards, Javier Francisco Nossa Postdoc at Geophysical Laboratory Carnegie Institution of Washington 5251 Broad Branch Road, N.W. Washington, DC 20015-1305 Tel.: 1.240.476.3993 E-mail: [email protected] <[email protected]>
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