[Pw_forum] Trouble with the Fe PBE PAW functional.

[Ari P Seitsonen]

Dear Joshua,

   Some intiial comments:

  - Have you understood the meaning of the variable 'ecutrho'? You are 
using PAWs so better use it :)

  - From the documentatino on "starting_magnetization":
      << Values range between -1 (all spins down for the valence
            electrons of atom type 'i') to 1 (all spins up). >>

   The value 6 is probably scaled down to 1, and the error here is not so 
big, and it is only for the initial density.

  - You will start, and probably obtain, a ferromagnetic ordering of spins, 
is this what you expect/want?

     Greetings from Rainy Paris,

        apsi

-=*=-=*=-=*=-=*=-=*=-=*=-=*=-=*=-=*=-=*=-=*=-=*=-=*=-=*=-=*=-=*=-=*=-=*=-=*=-
   Ari Paavo Seitsonen / Ari.P.Seitsonen at iki.fi / http://www.iki.fi/~apsi/
   Ecole Normale Supérieure (ENS), Département de Chimie, Paris
   Mobile (F) : +33 789 37 24 25    (CH) : +41 79 71 90 935


On Fri, 27 Mar 2015, Joshua Davis wrote:

> Dear QE users
> Summary: I am attempting a wave-function energy convergence on my Iron containing compound, but I am have confusing errors that include
> lack of electronic convergence, and the statement "g-vectors missing."  The suggested density cut-off is really high for Iron.  I think
> this may have some thing to do with the errors.
> 
> General:
> I am using QE 5.1 on Ubuntu 12.04 LTS The pseudopotentials I am using are:
> Li.pbe-s-kjpaw_psl.0.2.1.UPF
> Fe.pbe-spn-kjpaw_psl.0.2.1.UPF
> O.pbe-n-kjpaw_psl.0.1.UPF
> 
> The  general script I use to make my input files and run them is:
> 
>
>       #!/bin/bash
> ##################################################
> # This is a e-cut convergence  for a wave function
> # of a cell of LiFeO2. $ECUT is in Ry.
> ##################################################
> 
> for ECUT in 50 70 80 90 100 110 120 130 140 150 160
> do
> rm -rf ./scratch/*
> cat > LiFeO2_ec$ECUT.in << EOF
>  &CONTROL
>    title = 'LiFeO2ECUTtest',
>    calculation = 'vc-relax',
>    pseudo_dir = '../pot',
>    outdir = './scratch',
>    prefix = 'lifeo2ecut',
>    etot_conv_thr = 1.0D-5,
>    forc_conv_thr = 1.0D-4
>  /
> 
>  &SYSTEM
>    ibrav = 8,
>    a = 5.51600,
>    b = 6.41390,
>    c = 5.07890,
>    nat = 16,
>    ntyp = 3,
>    starting_magnetization(1) = 0,
>    starting_magnetization(2) = 6,
>    starting_magnetization(3) = 0,
>    ecutwfc = $ECUT,
>    nspin = 2,
>    occupations = 'smearing',
>    smearing = 'gaussian',
>    degauss = 2.0D-2
>  /
> 
>  &ELECTRONS
>    mixing_beta = 0.7,
>    electron_maxstep = 200,
>    conv_thr = 1.D-8
>  /
>  &IONS
>    ion_dynamics = 'bfgs'
>  /
> 
>  &CELL
>    cell_dynamics = 'bfgs',
>    cell_dofree = 'xyz'
>  /
> 
> ATOMIC_SPECIES
>  Li 6.94 Li.pbe-s-kjpaw_psl.0.2.1.UPF
>  Fe 55.845 Fe.pbe-spn-kjpaw_psl.0.2.1.UPF
>  O 15.999 O.pbe-n-kjpaw_psl.0.1.UPF
> 
> ATOMIC_POSITIONS (crystal)
> ...
> ...
> ..
> 
> 
> K_POINTS (gamma)
> 
> EOF
> 
> ----------------------------------------------------------------------------------------------------------------
> Joshua D. Davis
> 
> Graduate Assistant
> Department of Chemistry
> Michigan State University
> 
> 578 S. Shaw Lane, room 432
> 
> East Lansing, MI 48824
> -----------------------------------------------------------------------------------------------------------------
> 
>