Dear all, I am using linear response to determine U for Fe. In my system, there are two types of Fe atom, one in which the Fe is in an O octahedron and the second in which it is in an O terahedron. When I am plotting the occupation number of the Fe d as a function of perturbation alpha (-0.2 .le. alpha .le 0.2), for the non interacting electron system, I am not getting a linear plot for the whole range of alpha while for the interacting one it remains linear. For example when Fe is in the O octahedra, the response does not remain linear for alpha is greater than 0.05 or less than -0.05. However, for the interacting case, it remains linear for the whole regime (please refer to the attached plot for Fe in O octahedra). Further for this case for alpha=0, the occupation for the interacting and non interacting ones are not exactly same. While for the non-interacting one the occupation is 6.60012, it is 6.60162 for the interacting one.
Similarly for the tethedra, for alpha=-0.2, the non-interacting response does not remain linear while for the interacting one it remains linear. I was wondering whether one has faced similar situations and if so can provide me some hints as to what might be the probable reason for the same? Below is the input file I am using for the calculation: for alpha in -0.20 -0.15 -0.10 -0.05 0.00 0.05 0.10 0.15 0.20 do mkdir /scratch/pghosh/octfe/alpha$alpha cd /scratch/pghosh/octfe/alpha$alpha ethr=`grep ethr /home/pghosh/Ca2Fe2O5/octfe/scf.out | tail -1 | awk '{print $3}'` rm -rf Ca2Fe2O5-noU-vcrel-AFM.* cp -r ../Ca2Fe2O5-noU-vcrel-AFM.* . cat > scf-octFe.$alpha.in << EOF &control calculation = 'scf', prefix = 'Ca2Fe2O5-noU-vcrel-AFM', outdir = '/scratch/pghosh/octfe/alpha$alpha' pseudo_dir = '/home/pghosh/pseudo' / &system ibrav = 0, celldm(1)=10.25176385 nat = 36, ntyp = 5, ecutwfc = 45 ecutrho = 320 nspin=2 starting_magnetization(2)=-1.0 starting_magnetization(3)=1.0 starting_magnetization(4)=-1.0 occupations='smearing' degauss=0.001 smearing='gaussian' lda_plus_u = .true., U_projection_type = 'atomic', Hubbard_U(2) = 1.d-10 Hubbard_U(3) = 1.d-10 Hubbard_U(4) = 1.d-10 Hubbard_U(5) = 1.d-10 Hubbard_alpha(4) = $alpha / &electrons mixing_beta = 0.3 conv_thr = 1.0d-8, startingwfc = 'file', startingpot = 'file', diago_thr_init = $ethr / ATOMIC_SPECIES Ca 87.62 Ca.pw91-nsp-van.UPF Fe1 47.867 Fe.pw91-sp-van_ak.UPF Fe2 47.867 Fe.pw91-sp-van_ak.UPF Fe3 47.867 Fe.pw91-sp-van_ak.UPF O 15.999 O.pw91-van_ak.UPF ATOMIC_POSITIONS (crystal) Ca 0.479439516 0.108738866 0.023376810 Ca 0.979439516 0.391261134 0.476623190 Ca 0.520560484 0.608738866 0.976623190 Ca 0.020560484 0.891261134 0.523376810 Ca 0.520560484 0.891261134 0.976623190 Ca 0.020560484 0.608738866 0.523376810 Ca 0.479439516 0.391261134 0.023376810 Ca 0.979439516 0.108738866 0.476623190 Fe3 0.000000000 0.000000000 -0.000000000 Fe1 0.500000000 0.500000000 0.500000000 Fe1 0.000000000 0.500000000 -0.000000000 Fe1 0.500000000 -0.000000000 0.500000000 Fe2 0.948517158 0.250000000 0.935170308 Fe2 0.448517158 0.250000000 0.564829692 Fe2 0.051482842 0.750000000 0.064829692 Fe2 0.551482842 0.750000000 0.435170308 O 0.262959232 0.985181682 0.237331409 O 0.762959232 0.514818318 0.262668591 O 0.737040768 0.485181682 0.762668591 O 0.237040768 0.014818318 0.737331409 O 0.737040768 0.014818318 0.762668591 O 0.237040768 0.485181682 0.737331409 O 0.262959232 0.514818318 0.237331409 O 0.762959232 0.985181682 0.262668591 O 0.027189198 0.140319152 0.069344138 O 0.527189198 0.359680848 0.430655862 O 0.972810802 0.640319152 0.930655862 O 0.472810802 0.859680848 0.569344138 O 0.972810802 0.859680848 0.930655862 O 0.472810802 0.640319152 0.569344138 O 0.027189198 0.359680848 0.069344138 O 0.527189198 0.140319152 0.430655862 O 0.586951586 0.250000000 0.888451999 O 0.086951586 0.250000000 0.611548001 O 0.413048414 0.750000000 0.111548001 O 0.913048414 0.750000000 0.388451999 K_POINTS (automatic) 9 3 9 1 1 1 CELL_PARAMETERS (alat) 0.991167212 0.000000000 0.000000000 0.000000000 2.746908521 0.000000000 0.000000000 0.000000000 1.023657125 EOF With regards, Prasenjit -- PRASENJIT GHOSH, IISER Pune, Dr. Homi Bhabha Road, Pashan Pune, Maharashtra 411008, India Phone: +91 (20) 2590 8203 Fax: +91 (20) 2589 9790
_______________________________________________ Pw_forum mailing list Pw_forum@pwscf.org http://pwscf.org/mailman/listinfo/pw_forum