On Thu, May 26, 2016 at 12:43 AM, Qihang Liu <[email protected]> wrote:
> > if one forces the use_all_frac to be true he will get a imperfect > non-symmophic operation, the result is some of the representation of a > certain band cannot be defined, indicated with a "?". > well, it's not the symmetry operation that is imperfect: it is the algorithm that finds the representations that is imperfect, in my opinion. Symmetries exist in nature, FFT grids exist only in computer codes. Paolo > So the better way is to change nr1-nr3 to even numbers so that the code > will not have any trouble on non-symmophic operations and provide the group > representations you want. > > If there is anything wrong please correct me. Thanks. > > Best, > > > Qihang Liu > > Research Associate > Renewable and Sustainable Energy Institute (RASEI) > University of Colorado Boulder > Boulder, CO 80309-029 USA > https://www.colorado.edu/zunger-materials-by-design/qihang-liu > > On Wed, May 25, 2016 at 2:29 PM, Paolo Giannozzi <[email protected]> > wrote: > >> This is what I get with your input: >> >> 12 Sym. Ops., with inversion, found >> (note: 12 additional sym.ops. were found but ignored >> their fractional translations are incommensurate with FFT grid) >> >> while with option "use_all_frac=.true.", or by setting the FFT grid to >> nr1=50, nr2=50, nr3=80: >> >> 24 Sym. Ops., with inversion, found (12 have fractional translation) >> >> Paolo >> >> On Wed, May 25, 2016 at 8:36 PM, Qihang Liu <[email protected]> >> wrote: >> >>> Dear all, >>> >>> I am struggling with the band symmetry analysis on a structure with a >>> space group #194 P63/mmc (D_6h^4). I use the tag space_group to define it >>> so I suppose the space group can be realized correctly by pwscf. As we >>> know, the little group of Gamma point should follow the group of the >>> crystal structure which is also D_6h. The the output of QE is D_3d. Please >>> see the following input and outputs: >>> >>> scf.in >>> &control >>> prefix='bulk', >>> pseudo_dir='./' >>> outdir = './', >>> wf_collect = .true., >>> / >>> &system >>> ibrav= 4, >>> celldm(1)= 8.568018, celldm(3)= 1.660013, space_group = 194 >>> nat= 3, ntyp= 3, nbnd = 48, >>> ecutwfc = 36.0, ecutrho = 320.0, >>> lspinorb = .true., noncolin = .true., >>> occupations='smearing', smearing='gaussian', degauss=0.02, >>> / >>> &electrons >>> diagonalization='david', >>> conv_thr = 1.0e-8, >>> mixing_beta = 0.7, >>> / >>> ATOMIC_SPECIES >>> Li 6.941 Li.rel-pbe-s-kjpaw_psl.0.2.1.UPF >>> Hg 200.5 Hg.rel-pbe-dn-kjpaw_psl.0.2.2.UPF >>> As 74.922 As.rel-pbe-n-kjpaw_psl.0.2.UPF >>> ATOMIC_POSITIONS crystal_sg >>> Li 0.0000000000000000 0.0000000000000000 0.0000000000000000 >>> Hg 0.3333333300000021 0.6666666699999979 0.2500000000000000 >>> As 0.6666666699999979 0.3333333300000021 0.2500000000000000 >>> K_POINTS automatic >>> 9 9 6 0 0 0 >>> >>> nscf.in >>> &control >>> calculation = 'nscf' >>> prefix='bulk', >>> pseudo_dir='./' >>> outdir = './', >>> wf_collect = .true., >>> / >>> &system >>> ibrav= 4, >>> celldm(1)= 8.568018, celldm(3)= 1.660013, space_group = 194 >>> nat= 3, ntyp= 3, nbnd = 48, >>> ecutwfc = 36.0, ecutrho = 320.0, >>> lspinorb = .true., noncolin = .true., >>> occupations='smearing', smearing='gaussian', degauss=0.02, >>> / >>> &electrons >>> diagonalization='david', >>> conv_thr = 1.0e-8, >>> mixing_beta = 0.7, >>> / >>> ATOMIC_SPECIES >>> Li 6.941 Li.rel-pbe-s-kjpaw_psl.0.2.1.UPF >>> Hg 200.5 Hg.rel-pbe-dn-kjpaw_psl.0.2.2.UPF >>> As 74.922 As.rel-pbe-n-kjpaw_psl.0.2.UPF >>> ATOMIC_POSITIONS crystal_sg >>> Li 0.0000000000000000 0.0000000000000000 0.0000000000000000 >>> Hg 0.3333333300000021 0.6666666699999979 0.2500000000000000 >>> As 0.6666666699999979 0.3333333300000021 0.2500000000000000 >>> K_POINTS crystal_b >>> 3 >>> 0 0 0 30 ! Gamma >>> 0 0 0.5 30 ! A >>> 0.5 0 0.5 1 ! L >>> >>> bands.in >>> &bands >>> prefix = 'bulk', >>> outdir='./', >>> filband = 'bands.dat', >>> lsym = .true., >>> / >>> >>> Output: >>> >>> ************************************************************************** >>> >>> xk=( 0.00000, 0.00000, 0.00000 ) >>> >>> double point group D_3d (-3m) >>> there are 12 classes and 6 irreducible representations >>> the character table: >>> >>> E -E 2C3 -2C3 3C2' -3C2' i -i 2S6 -2S6 3s_v >>> -3s_v >>> >>> G_4+ 2.00 -2.00 1.00 -1.00 0.00 0.00 2.00 -2.00 1.00 -1.00 0.00 >>> 0.00 >>> G_5+ 1.00 -1.00 -1.00 1.00 0.00 0.00 1.00 -1.00 -1.00 1.00 0.00 >>> 0.00 >>> G_6+ 1.00 -1.00 -1.00 1.00 0.00 0.00 1.00 -1.00 -1.00 1.00 0.00 >>> 0.00 >>> G_4- 2.00 -2.00 1.00 -1.00 0.00 0.00 -2.00 2.00 -1.00 1.00 0.00 >>> 0.00 >>> G_5- 1.00 -1.00 -1.00 1.00 0.00 0.00 -1.00 1.00 1.00 -1.00 0.00 >>> 0.00 >>> G_6- 1.00 -1.00 -1.00 1.00 0.00 0.00 -1.00 1.00 1.00 -1.00 0.00 >>> 0.00 >>> >>> Can anyone help me to explain the inconsistency? Is is related to some >>> non-symmophic symmetries that QE can not deal with? Thanks a lot. >>> >>> Best, >>> >>> Qihang Liu >>> >>> Research Associate >>> Renewable and Sustainable Energy Institute (RASEI) >>> University of Colorado Boulder >>> Boulder, CO 80309-029 USA >>> https://www.colorado.edu/zunger-materials-by-design/qihang-liu >>> >>> >>> _______________________________________________ >>> Pw_forum mailing list >>> [email protected] >>> http://pwscf.org/mailman/listinfo/pw_forum >>> >> >> >> >> -- >> Paolo Giannozzi, Dip. Scienze Matematiche Informatiche e Fisiche, >> Univ. Udine, via delle Scienze 208, 33100 Udine, Italy >> Phone +39-0432-558216, fax +39-0432-558222 >> >> >> _______________________________________________ >> Pw_forum mailing list >> [email protected] >> http://pwscf.org/mailman/listinfo/pw_forum >> > > > _______________________________________________ > Pw_forum mailing list > [email protected] > http://pwscf.org/mailman/listinfo/pw_forum > -- Paolo Giannozzi, Dip. Scienze Matematiche Informatiche e Fisiche, Univ. Udine, via delle Scienze 208, 33100 Udine, Italy Phone +39-0432-558216, fax +39-0432-558222
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