Hi, You need to figure out numbers of each atomic specie and positions of each atom, ibrav = 2 only gives you three fcc lattice vectors. I don't think it implies fd3m space group.
Bests Jia On Mon, Aug 6, 2012 at 10:42 AM, Abolore Musari <abmus007 at gmail.com> wrote: > Thanks so much Jia > But Sir the atomic positions in the input is for 3 atoms, should l leave > the atomic position and change the number of atom or my atomic position is > wrong?? > thanks > Musari A. A > UNAAB Nigeria > > > On Mon, Aug 6, 2012 at 3:34 PM, jia chen <jiachen at princeton.edu> wrote: > >> Dear Abolore Musari, >> >> I guess the number of atoms should be 14, instead of 3. >> >> Regards >> Jia >> >> On Mon, Aug 6, 2012 at 10:24 AM, Abolore Musari <abmus007 at gmail.com>wrote: >> >>> Dear QE users >>> Sir, I am try to find the lattice constant of magnetite (Fe3O4) which is >>> a spinel ferrimagnetic material. The expt lattice constant was 15.87 and I >>> have been trying to find the equilibrium lattice constant (celldm(1)) >>> between 15.80 - 16.00 and all i get is a straight line graph instead of the >>> usual exponential curve graph. I have tried all l could most esp with >>> starting_magnetization but the results are the same. My input is pasted >>> below pls help me to get the appropriate graph. >>> The kind of the graph I got is attached. >>> Thanks >>> >>> &control >>> calculation = 'scf', >>> restart_mode ='from_scratch', >>> prefix = 'Fe3O4', >>> pseudo_dir = '/home/abolore/Programs/Pseudos/', >>> outdir = './tmp/' >>> / >>> &system >>> ibrav = 2, >>> celldm(1)= $15.80-16.00, >>> nat = 3, >>> ntyp = 3, >>> ecutwfc = 40, >>> ecutrho = 400, >>> starting_magnetization(1) = 0.7, >>> starting_magnetization(2) = -0.5, >>> starting_magnetization(3) = 0.0, >>> nspin = 2, >>> occupations='smearing', >>> smearing='gaussian', >>> degauss = 0.05, >>> / >>> &electrons >>> diagonalization = 'david', >>> mixing_mode = 'plain', >>> mixing_beta = 0.7 >>> / >>> ATOMIC_SPECIES >>> Fe1 55.845 Fe.pz-nd-rrkjus.UPF >>> Fe2 55.845 Fe.pz-nd-rrkjus.UPF >>> O 16.000 O.pz-rrkjus.UPF >>> >>> ATOMIC_POSITIONS >>> Fe1 0.125 0.125 0.125 >>> Fe2 0.500 0.500 0.500 >>> O 0.2548 0.2548 0.2548 >>> >>> K_POINTS (automatic) >>> 8 8 8 1 1 1 >>> >>> >>> >>> >>> >>> >>> >>> >>> >>> >>> >>> >>> >>> >>> >>> >>> >>> _______________________________________________ >>> Pw_forum mailing list >>> Pw_forum at pwscf.org >>> http://www.democritos.it/mailman/listinfo/pw_forum >>> >>> >> >> >> -- >> Jia Chen >> >> >> >> _______________________________________________ >> Pw_forum mailing list >> Pw_forum at pwscf.org >> http://www.democritos.it/mailman/listinfo/pw_forum >> >> > > _______________________________________________ > Pw_forum mailing list > Pw_forum at pwscf.org > http://www.democritos.it/mailman/listinfo/pw_forum > > -- Jia Chen Dept of Chemistry Princeton University Princeton, NJ 08544 -------------- next part -------------- An HTML attachment was scrubbed... URL: http://www.democritos.it/pipermail/pw_forum/attachments/20120806/e02bd38b/attachment-0001.htm
