[Pw_forum] Fwd: Basic Relax Calculation issues

[Zarah Baiyee]

Thanks Fillipe,
I am currently having a few issues with VC-Relax input files and cannot
seem to get them to work, please find attached. I consistently get an
error:

     Error in routine dos (1):
     reading dos namelist

Any suggestions would be greatly appreciated.

Thanks

Zarah




On Fri, Mar 7, 2014 at 11:35 AM, Filipe Camargo Dalmatti Alves Lima <
flima at if.usp.br> wrote:

> Dear Zarah,
>
> Have you ever considered that you may want the cell relaxation in this
> case? (vc-relax)
> It will optimize the cell parameter in order to minimize the total energy.
> You'll see that the system might have lots of interactions.
>
> If you want to explore defects in crystals or surfaces, relaxing the
> internal coordinates are essential since you are breaking the symmetry in
> some way: by having impurities; surface interaction; vacancy defects and
> etc. If it is the case you want to explore, you will need to use a
> supercell approach. Remember: crystals are built based on symmetry rules.
>
> If you are really curious, you might try to change the cell symmetry just
> to observe how the internal coordinations behave (just increase z by 0.2).
> It may not converge, but you will see a lot interactions.
>
> Best regards,
>
> Filipe
>
> On Friday, February 28, 2014, Zarah Baiyee <z.baiyee at gmail.com> wrote:
>
>> Hi All,
>>
>> I am a new user to Quantum Espresso, therefore this may be a bit trivial
>> but I any help would be very welcome.
>>
>> I am attempting a relax calculation using espresso version 5.0.2, for the
>> geometry optimisation of a perovskite structure. For the input below, the
>> calculation runs, however does not compute any forces and convergence
>> without geometry optimisation to the original structure, with 0 bfgs steps.
>> I am able to perform an expected relaxation if alter the initial atomic
>> positions to asymmetric: (i.e.)  an oxygen molecule from:  O (0.500  0.5
>>  0.0) to O(0.499 0.5 0.0).
>>
>> Please may someone shed some light on to why this is the case, and if
>> there is anything wrong with my input.
>>
>> Thanks
>>
>> Zarah
>> Zbaiyee at gmail.com
>>
>> &CONTROL
>>   calculation  = "relax",
>>   prefix       = "CO",
>>   pseudo_dir   = "/Users/zarahbaiyee/espresso-5.0.2/pseudo",
>>   outdir       = "/Users/zarahbaiyee/tmp",
>>   forc_conv_thr = 1.0D-5
>> /
>> &SYSTEM
>>   ibrav     = 0,
>>   nat       = 5,
>>   ntyp      = 3,
>>   ecutwfc   = 60,
>>   ecutrho   = 420,
>> /
>> &ELECTRONS
>>   conv_thr    = 1.D-7,
>>   mixing_beta = 0.7D0,
>>   electron_maxstep = 400
>> /
>> &IONS
>> /
>> CELL_PARAMETERS bohr
>>  7.60  0.0  0.0
>>  0.0  7.60  0.0
>>  0.0  0.0  7.60
>> ATOMIC_SPECIES
>>  Ba  137.32 Ba.pbe-mt_fhi.UPF
>>  Fe  55.84 Fe.pbe-mt_fhi.UPF
>>  O   15.99 O.pbe-kjpaw.UPF
>> ATOMIC_POSITIONS {crystal}
>> Ba  0.000  0.0  0.0  0 0 0
>> Fe  0.500  0.5  0.5
>> O   0.000  0.5  0.5
>> O   0.500  0.0  0.5
>> O   0.500  0.5  0.0
>> K_POINTS {automatic}
>> 9 9 9 0 0 0
>>
>>
>
> --
> _________________________________________
> Filipe Camargo Dalmatti Alves Lima
> PhD Student
> University of São Paulo, Physics Institute, Materials Physics Department,
> Nanomol Group, Brazil.
> Phones:    (11) 3091-6881  (USP)
>                 (11) 97408-2755 (Vivo)
>
>
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