[Pw_forum] equilibrium lattice constant of magnetite

[Abolore Musari]

Thanks bamidele.
It will be appreciated if u can assist with the said material. thanks for
the infomation and thanking you in anticipation of favourable assiatance

Musari A.A
On Mon, Aug 6, 2012 at 3:58 PM, bamidele ibrahim
<bamideleibrahim at yahoo.com>wrote:

> Dear Abolore,
> Read this article it contains all the atomic positions for the compound.
> You need to know that for this compound Z=8.
> http://www.springerlink.com/content/p27870432mt31374/fulltext.pdf
>
> Adetunji Bamidele Ibrahim(PhD Student)
> Department of physics,University of Agriculture,
> Abeokuta, Ogun State,Nigeria.
>
>   ------------------------------
> *From:* Abolore Musari <abmus007 at gmail.com>
> *To:* PWSCF Forum <pw_forum at pwscf.org>
> *Sent:* Monday, August 6, 2012 4:42 PM
> *Subject:* Re: [Pw_forum] equilibrium lattice constant of magnetite
>
> 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
>
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> --
> Jia Chen
>
>
>
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