[Pw_forum] RE : Lattice Parameter too low from experimentally determined. (3.42 ~ 3.52)

[Elliot Menkah]

On 12/03/2013 12:19 PM, BARRETEAU Cyrille wrote:
> Dear Eliot
>
> You should probably use a GGA pseudopotential (Ni.pz-nd-rrkjus.UPF is LDA) and also increase the number of kpoints (7 7 7 is too low especially for magnetic systems).
>
> Cyrille
>
> -----------------------------------------------------------------------------------------------------------
> Cyrille Barreteau
> CEA Saclay, IRAMIS, SPCSI, Bat. 462
> 91191 Gif sur Yvette Cedex, FRANCE
> ~~~~~~~~~~~~~~~~~~~~~~~~~~~~
> phone:    +33 (0)1 69 08 29 51 / +33 (0)6 47 53 66 52
> fax :       +33 (0)1 69 08 84 46
> email:     cyrille.barreteau at cea.fr
> Web:     http://iramis.cea.fr/Pisp/cyrille.barreteau/
>   -----------------------------------------------------------------------------------------------------------
>
> ________________________________________
> De : pw_forum-bounces at pwscf.org [pw_forum-bounces at pwscf.org] de la part de Elliot Menkah [elliotsmenkah at yahoo.com]
> Date d'envoi : mardi 3 décembre 2013 13:04
> À : pw_forum at pwscf.org
> Objet : [Pw_forum] Lattice Parameter too low from experimentally determined. (3.42 ~ 3.52)
>
> Hi all,
>
> I'm determining the lattice parameter of Nickel and my convergence test
> is giving me 3.42 Angstroms against and experimentally determined 3.52.
> Previous calculations by other people are showing 3.49 and 3.52
> Angstroms as again.
>
> What could be wrong with my parameters or calculations.
>
> Below is the input file please.
>
>
> #!/bin/sh
> # check whether echo needs the -e option
> #
> executablepath=/home/molecular/espresso-5.0.2/bin/pw.x
> for alat in  6.273 6.369 6.463 6.557 6.652 6.746 6.841 6.935
> do
> #input file
> cat > Ni-$alat.in << EOF
> &CONTROL
>          title = 'Ni-ferro-mag' ,
>          calculation = 'relax' ,
>          restart_mode = 'from_scratch' ,
>          outdir = './temp' ,
>          pseudo_dir = '/home/molecular/Elliot/pseudo' ,
>          prefix = 'Ni-ferromag',
>          tstress = .true. ,
>          tprnfor = .true. ,
> /
>    &SYSTEM
>          ibrav = 2,
>          celldm(1) = $alat,
>          nat = 1,
>          ntyp = 1,
>          ecutwfc = 60,
>          ecutrho = 480,
>          occupations='smearing',
>          smearing='fermi-dirac',
>          degauss=0.003,
>          nbnd=10
>          nspin=2,
>          starting_magnetization(1)=0.5,
> /
>    &ELECTRONS
>           conv_thr = 1.0D-8
>           mixing_beta = 0.2,
> /
>    &IONS
> /
> ATOMIC_SPECIES
>           Ni1 58.6934   Ni.pz-nd-rrkjus.UPF
> ATOMIC_POSITIONS (alat)
>          Ni1       0.000000000   0.000000000   0.000000000
> K_POINTS automatic
>     7 7 7   0 0 0
>
> EOF
> $executablepath < Ni-$alat.in > Ni-$alat.out
> grep "Final energy" Ni-$alat.out >> Ell0.txt
> echo "$alat" >> Lat.txt
> done
> awk '{print $4}' Ell0.txt > Nel.txt
> paste Lat.txt Nel.txt > Final_alat.txt
>
> rm Lat.txt Ell0.txt
>
>
> Thank uou.
>
>
>
> Kind regards,
>
> ELliot.
>
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Ok.

Thank you very much.

Can you please advice me on which of the various pseudo-potentials of 
Nickel that is a GGA pseudo potential please.

I appreciate