[Pw_forum] Interface and Vacuum

[Giovanni Cantele]

The ibrav=0 is usually needed if you want to setup a unit cell that is not a default one in QE (see INPUT_PW.txt, under the description of ibrav).

If the unit cell you mentioned is just that you need (that is, if you have correctly setup the interface), it is orthorhombic, so in that case you can use the corresponding
ibrav. However, even with ibrav=0 setting up the vacuum is achieved just by increasing the length of the unit cell vector orthogonal to the interface.

If instead you question was also about how to build the interface, you should also specify which TiO2 and Cu surfaces you’re interested in.

Giovanni

> On 05 Apr 2016, at 12:09, Sarah Alpine <sarahalpine1 at gmail.com> wrote:
> 
> If anyone has any suggestions, I'd really appreciate it. Thanks!
> 
> On Wed, Mar 30, 2016 at 11:28 AM, Sarah Alpine <sarahalpine1 at gmail.com <mailto:sarahalpine1 at gmail.com>> wrote:
> Dear All,
>     I am simulating a Copper-TiO2 interface, and since Copper is FCC and TiO2 is tetragonal, I think I need to use ibrav=0. In that case, how do I set up the vacuum around the interface?
> Thanks,
> Sarah
> 
> &CONTROL
>   calculation='vc-relax',
>   outdir='.',
>   prefix='calc',
>   pseudo_dir = './',
>   verbosity='high',
>   tstress=.true.,
>   tprnfor=.true.,
> /
> 
> &SYSTEM
>   ibrav=0,
>   celldm(1)=20.4938530538d0,
>   nat=35,
>   ntyp=3,
>   ecutwfc=40,
>   ecutrho=200,
>   occupations='smearing',
>   smearing='gaussian',
>   degauss=0.01
> /
> 
> &ELECTRONS
>   diagonalization='david',
>   conv_thr=1d-08,
>   mixing_mode='plain',
>   mixing_beta=0.7,
> /
> 
> ATOMIC_SPECIES
>   Cu 63.546000d0 Cu.pw-mt_fhi.UPF
>   O 15.999400d0  O.pw-mt_fhi.UPF
>   Ti 47.867000d0 Ti.pw-mt_fhi.UPF
> 
> ATOMIC_POSITIONS {alat}
>   Cu   0.1666666667d0  -0.1178511302d0   0.1178511302d0
> ...
> 
> 
> K_POINTS {automatic}
>   8 8 8 1 1 1
> 
> CELL_PARAMETERS {alat}
>   1.000000000000d0  0.000000000000d0  0.000000000000d0
>   0.000000000000d0  -0.471404520791d0  0.000000000000d0
>   0.000000000000d0  0.000000000000d0  1.618839606572d0
> 
> 
> 
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-- 

Giovanni Cantele, PhD
CNR-SPIN
c/o Dipartimento di Fisica
Universita' di Napoli "Federico II"
Complesso Universitario M. S. Angelo - Ed. 6
Via Cintia, I-80126, Napoli, Italy
e-mail: giovanni.cantele at spin.cnr.it
Phone: +39 081 676910
Skype contact: giocan74

ResearcherID: http://www.researcherid.com/rid/A-1951-2009
Web page: http://people.na.infn.it/~cantele

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