Dear Davide, The structure is gamma (tetragonal symmetry) according to J. Chem. Phys. 44, 3348 (1966), all borons are tetrahedrally coordinated to oxygen. Convention is ok. i think.
There might be some confusion in the literature indeed. I will re-check for other system ans report asap. Thanks for help, best regards, Zibi ---------- Original Message ----------- From: Davide Ceresoli <[email protected]> To: PWSCF Forum <pw_forum at pwscf.org> Sent: Wed, 12 Sep 2012 10:32:11 +0200 Subject: Re: [Pw_forum] quadrupole monents & GIPAW & a problem > Dear Zibi, > could you check with me whether your crystal is the gamma > phase? experiments report Cq=0.042 MHz and eta=0.0 (Vorotilova, > Dmitrieva and Samoson, 1987). B is an nearly cubic environment > and the tetragonal symmetry should yield an axial tensor, hence > vanishing eta. > > Anyway, I recognize that B.pbe-tm-gipaw.UPF has some problems. > It did work for NMR of small molecules, but I never tested it > in solid state systems, I'm sorry. > > The last thing to check, is the tensor convention. I think I'm > using the Haeberlen convention, which is the same used by the > Simpson code > > (http://anorganik.uni- > tuebingen.de/klaus/nmr/index.php?p=conventions/csa/csa). > > HTH. > > Best, > Davide > > On 09/11/2012 06:00 PM, Zbigniew Lodziana wrote: > > Dear users & developers, > > > > While calculating quadrupole moments with GIPAW I have experienced a strange > > output that confuses me and it is difficult for interpretation, at least to me. > > > > Performing calculations for LiBO2 (with occupancies = fixed!) efg > > calculations > > provide for Boron: > > (a) Cq= 0.0208 MHz eta= 0.00000 > > (b) Cq= 2.0747 MHz eta= 0.00000 > > (c) Cq= 0.0228 MHz eta= 0.00000 > > > > Where > > (a) is with TM potential > > [https://sites.google.com/site/dceresoli/pseudopotentials/B.pbe-tm-new-gipaw-dc.UPF?attredirects=0]; > > > > (b) also TM > > [https://sites.google.com/site/dceresoli/pseudopotentials/B.pbe-tm-gipaw.UPF?attredirects=0]; > > > > (c) with ultrasoft. > > > > Experimental value is Cq=2.56, eta=0.6; theoretical report Cq=2.552, > > eta=0.54 > > > > Test calculations with other more accurate potentials unfortunately do not > > solve problem. > > > > And the problem is that the worst description of the valence states provides > > (at least numerically) best Cq; besides it is difficult to understand how > > small changes in the valence state might result in so large ? two orders of > > magnitude ? changes in the core region. For other systems changes are even 3 > > orders. > > > > Structural parameters are reasonable. > > > > For oxygen I did not found such a large variations, for Al Cq is reasonable. > > > > Does anyone experienced similar problems or has any hint where the problem > > could origin form? > > > > Thank you in advance, > > Best regards, > > > > Zibi > > > > > > Pw.x ? 5.0 > > Gipaw.x 5.0 > > (version 4.3a gives similar results) > > ----------------------------------- > > Pw.x > > > > &control > > calculation = 'scf' > > prefix = 'LiBO2' > > restart_mode = 'from_scratch' > > pseudo_dir = './pseudo/' > > outdir = './tmp/' > > verbosity = 'high' > > wf_collect=.true. > > / > > &system > > ibrav = 0 > > celldm(1) = 1.0 > > nat = 16 > > ntyp = 3 > > ecutwfc = 110 > > ecutrho = 1000 > > spline_ps = .true. > > occupations = 'fixed' > > / > > &electrons > > diagonalization = 'david' > > diago_thr_init = 1e-4 > > mixing_mode = 'plain' > > mixing_beta = 0.1 > > conv_thr = 1e-10 > > / > > > > ATOMIC_SPECIES > > Li 6.941 Li.pbe-tm-gipaw-dc.UPF > > B 10.811 B.pbe-tm-gipaw.UPF > > O 15.999 O.pbe-tm-new-gipaw-dc.UPF > > > > CELL_PARAMETERS (alat= 1.00000000) > > 8.020588949 0.000000000 0.000000000 > > 0.000000000 8.020588949 0.000000000 > > 0.000000000 0.000000000 12.497695405 > > > > ATOMIC_POSITIONS (crystal) > > Li 0.000000000 0.000000000 0.500000000 > > Li 0.500000000 0.000000000 0.249999998 > > Li 0.500000000 0.500000000 0.000000000 > > Li 0.000000000 0.500000000 0.750000002 > > B 0.000000000 0.000000000 0.000000000 > > B 0.500000000 0.000000000 0.750000000 > > B 0.500000000 0.500000000 0.500000000 > > B 0.000000000 0.500000000 0.250000000 > > O 0.154649384 0.249987860 0.125014658 > > O 0.845350616 0.750012140 0.125014658 > > O 0.249987860 0.845350616 0.874985342 > > O 0.750012140 0.154649384 0.874985342 > > O 0.345350616 0.250012141 0.625014658 > > O 0.654649384 0.749987859 0.625014658 > > O 0.749987859 0.345350616 0.374985342 > > O 0.250012141 0.654649384 0.374985342 > > > > K_POINTS automatic > > 4 4 4 1 1 1 > > ------------------------------------------ > > Gipaw.x > > > > &inputgipaw > > job = 'efg' > > prefix = 'LiBO2' > > tmp_dir = './tmp/' > > iverbosity = 11 > > spline_ps = .true. > > Q_efg(1) = 4.06 ! 7Li > > Q_efg(2) = 4.06 ! 11B > > Q_efg(3) = 2.55 ! 17O > > ! q_gipaw = 0.01 > > / > > Q_efg for Li might not be perfect but shall not matter. > > > > > > -- > +--------------------------------------------------------------+ > Davide Ceresoli > CNR Institute of Molecular Science and Technology (CNR-ISTM) > c/o University of Milan, via Golgi 19, 20133 Milan, Italy > Email: davide.ceresoli at istm.cnr.it > Phone: +39-02-50314276, +39-347-1001570 (mobile) > Skype: dceresoli > +--------------------------------------------------------------+ > _______________________________________________ > Pw_forum mailing list > Pw_forum at pwscf.org > http://www.democritos.it/mailman/listinfo/pw_forum ------- End of Original Message -------
