[Pw_forum] convergence problem of FePc molecule

[Vincenzo Verdolino]

Hi,


i completely agree with Thomas. As I understand this should not be a metal
and you should not encounter troubles integrating around the Fermi level.
So I would not specify smearing and degauss (which should be around 0.01
anyway if you really have to). Moreover, I am not entirely sure about
placing the starting magnetization on C atom type...i would rather place it
on iron and (most important) would start with a 0.6 value in order to avoid
sticking in magnetic troubling states. Finally, how did you generate the
structure? Where does it come from? And your box specification? Cut off is
low, i agree, but should not be the problem...however i would set it at
least around 40 because you are far from convergency anyway!Very last
thing...you should start with electronic threshold set to the default.

Best regards

Vincenzo


On Mon, Sep 1, 2014 at 1:57 PM, 琨陶 <taokun76 at gmail.com> wrote:

> Dear all,
>
> I just start to learn Quantum Espresso, and want to optimize the geometry
> of an FePc molecule. But, it doesn't converge even after 500 steps. Could
> you give me some suggestions? Any suggestions are welcome!
>
> Regards,
> Kun Tao
>
>
> Attached below is the input file:
>
> &CONTROL
>     calculation = 'scf'
>     restart_mode='from_scratch',
>     prefix='FePc',
>     pseudo_dir = './',
>     outdir='./temp'
>     etot_conv_thr=1.D-4
>     forc_conv_thr=1.D-2
>  /
>  &SYSTEM
>    ibrav=6,
>    celldm(1)=41.58,
>    celldm(3)=0.454545,
>    nat=  57,
>    ntyp= 4,
>    ecutwfc = 27.0,
>    ecutrho = 250.0,
>   & occupations='fixed',
>    smearing='marzari-vanderbilt',
>    degauss=0.1,
>    nspin=2,
>    assume_isolated = 'martyna-tuckerman'
>    starting_magnetization(1)= 1,
>   & lda_plus_u = .true.
>   & Hubbard_U(1)= 1.d-20
>   & Hubbard_U(2)= 1.d-20
>   & nbnd = 380
>  /
>  &ELECTRONS
>    diagonalization='cg',
>    conv_thr    = 1.D-4,
>    mixing_beta = 0.05D0,
>    electron_maxstep = 500,
>  /
> &IONS
>   & ion_dynamics = 'bfgs'
>    bfgs_ndim = 3
> /
> ATOMIC_SPECIES
>   C  12.0  C.pw91-van_ak.UPF
>   H  1.0  H.pw91-van_ak.UPF
>   N  14.0  N.pw91-van_ak.UPF
>   Fe 55.8  Fe.pw91-sp-van_ak.UPF
> ATOMIC_POSITIONS {Angstrom}
>  C   12.15539372    13.73909330    5.04996061
>  C   13.73649156    12.16178989    5.05578041
>  C   13.43098617    14.43384445    5.05163491
>  C   14.42783630    13.43936718    5.06136000
>  C   13.76218534    15.79065418    5.04836023
>  C   15.78316009    13.77488291    5.07699788
>  C   13.73909330    9.84460628    5.04996061
>  C   12.16178989    8.26350933    5.05578041
>  C   14.43384445    8.56901383    5.05163491
>  C   13.43936718    7.57216460    5.06136000
>  C   15.79065418    8.23781467    5.04836023
>  C   13.77488291    6.21683902    5.07699788
>  C   9.84460628    8.26090580    5.04996061
>  C   8.26350933    9.83821011    5.05578041
>  C   8.56901383    7.56615555    5.05163491
>  C   7.57216460    8.56063193    5.06136000
>  C   8.23781467    6.20934671    5.04836023
>  C   6.21683902    8.22511798    5.07699788
>  C   8.26090580    12.15539372    5.04996061
>  C   9.83821011    13.73649156    5.05578041
>  C   7.56615555    13.43098617    5.05163491
>  C   8.56063193    14.42783630    5.06136000
>  C   6.20934671    13.76218534    5.04836023
>  C   8.22511798    15.78316009    5.07699788
>  C   6.87043524    16.11305392    5.07808685
>  C   5.87526149    15.11545813    5.06072640
>  C   5.88694608    6.87043524    5.07808685
>  C   6.88454098    5.87526149    5.06072640
>  C   15.11545813    16.12473762    5.06072640
>  C   16.11305392    15.12956476    5.07808685
>  C   16.12473762    6.88454098    5.06072640
>  C   15.12956476    5.88694608    5.07808685
>  H   12.98551416    16.55329919    5.03687501
>  H   16.54878414    13.00105667    5.08993745
>  H   16.55329919    9.01448494    5.03687501
>  H   13.00105667    5.45121586    5.08993745
>  H   9.01448494    5.44669992    5.03687501
>  H   5.45121586    8.99894244    5.08993745
>  H   5.44669992    12.98551416    5.03687501
>  H   8.99894244    16.54878414    5.08993745
>  H   6.57077259    17.16044581    5.09259462
>  H   4.82672697    15.41213369    5.05869567
>  H   4.83955419    6.57077259    5.09259462
>  H   6.58786541    4.82672697    5.05869567
>  H   15.41213369    17.17327213    5.05869567
>  H   17.16044581    15.42922831    5.09259462
>  H   17.17327213    6.58786541    5.05869567
>  H   15.42922831    4.83955419    5.09259462
>  N   12.36901915    9.63413960    5.05092382
>  N   9.63413960    9.63097996    5.05092382
>  N   9.63097996    12.36585951    5.05092382
>  N   14.37677419    11.00406444    5.05336285
>  N   11.00406444    7.62322491    5.05336285
>  N   7.62322491    10.99593645    5.05336285
>  N   10.99593645    14.37677419    5.05336285
>  N   12.36585951    12.36901915    5.05092382
>  Fe   11.00000000    11.00000000    5.04961908
> K_POINTS Gamma
>
> _______________________________________________
> Pw_forum mailing list
> Pw_forum at pwscf.org
> http://pwscf.org/mailman/listinfo/pw_forum
>
-------------- next part --------------
An HTML attachment was scrubbed...
URL: <http://lists.quantum-espresso.org/pipermail/users/attachments/20140901/65ffe02e/attachment.html>