[Pw_forum] Orienting Nickel 111-P(3x3) slab surface
Ari P Seitsonen
Ari.P.Seitsonen at iki.fi
Mon Dec 30 17:53:22 CET 2013
Now I _think_ that I know what your problem is. For similar systems I
use 'ibrav = 4', hexagonal cell that is (one needs to specify "a" and
"c", the angle is automatically the 120 degrees), and I either use "alat"
or "crystal" as the unit for the atomic coordinates: The former has the
advantage that the coordinates along the z axis (along the surface normal)
are independent of the length of your cell in that direction (value of
"c"), the latter that laterally the coordinates are simpler to insert.
As an example, attached please find my input for an eight-layer slab of
Au(111) (non-reconstructed, ie no Herringbone reconstruction but 1x1
laterally). You naturally would have to adapt the values for "a" and "c",
create the 3x3 cell laterally (division by three and translations by 1/3
of the new "a"), in principle the coordinates along z should not be
changed. And of course the number of k points along the lateral dimensions
of the Brillouin zone, amount of vacuum between the two sides of the slab
etc are up to you.
Hopefully this helps; please let us know if you need further
clarifications, or this is not what you wanted.
PS No warranty about correctness though. :)
Ari P Seitsonen / Ari.P.Seitsonen at iki.fi / http://www.iki.fi/~apsi/
Physikalisch-Chemisches Institut der Universitaet Zuerich
Tel: +41 44 63 54 497 / Mobile: +41 79 71 90 935
On Mon, 30 Dec 2013, Elliot Menkah wrote:
> Dear Apsi,
> I might be getting the description wrong but what I want to do is to place an
> adsorbate(Carbon monoxide) on the surface and run a calculation to get the
> energy involved.
> And the literature I have seen, which is guiding me, has the crystal cell
> looking perfectly like a well-oriented-vertical-standing cell (I do hope you
> I have attached a png file of the surface i have.
> But do I need to do something about the way a cell looks before I place
> adsorbates on a surface to run calculations on them please.
> Literature: Density functional theory study of the effect of alloying
> additions on sulfur adsorption on nickel surfaces.
> Authors : Oleksaandr I. Malyi, Ping Wu
> Applied Science 264(2013) 320-328
> Thank you,
> Happy Holidays,
> Elliot S. Menkah
> Research Student - Computational Chemistry/ Computational Material Science
> Theoretical and Computational Chemistry
> Dept. of Chemistry
> Kwame Nkrumah UNiversity of Sci. and Tech.
> Tel: +233 243-055-717
> Alt Email: elliotsmenkah at gmail.com
> elliotsmenkah at hotmail.com
-------------- next part --------------
calculation = 'relax'
restart_mode = 'from_scratch'
prefix = '1x1-clean-lrs_08'
pseudo_dir = './PP_LIBRARY/'
outdir = './scratch/'
tstress = .true.
tprnfor = .true.
verbosity = 'high'
etot_conv_thr = 1e-6
forc_conv_thr = 1e-5
ibrav = 4
a = 2.94616040381375026041
c = 50
ntyp = 1
nat = 08
nbnd = 60
occupations = 'smearing'
smearing = 'fermi-dirac'
degauss = 0.0036749326
ecutwfc = 35
ecutrho = 500
nspin = 1
conv_thr = 1e-9
mixing_beta = 0.7
Au 1.00 Au.pbe-dn-kjpaw_psl.0.3.0.UPF
Au 0.500000000 0.288675135 -2.85773803324704111452
Au 0.000000000 0.577350269 -2.04124145231931508180
Au 0.000000000 -0.000000000 -1.22474487139158904908
Au 0.500000000 0.288675135 -0.40824829046386301636
Au 0.000000000 0.577350269 0.40824829046386301636
Au 0.000000000 0.000000000 1.22474487139158904908
Au 0.500000000 0.288675135 2.04124145231931508180
Au 0.000000000 0.577350269 2.85773803324704111452
2*12 1 0 0 0
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