[Pw_forum] Doubt in workfunction example for Al100

[Bipul Rakshit]

Really thanks for your suggestion Giovanni,
I just have few more doubts that if i want to find the work function of
Au-ZnO Slab. I have created Au(111) and ZnO(0001) Slab. So it has an
interface of Zn-Au and a vacuum of 10 Angstrom. I took 6 layers of Au and 4
double layers of ZnO. Then how to proceed.
Means
1) Which two consecutive atomic planes I have to choose Au-Au, Au-Zn or the
Zn-O planes. for the microscopic average calculation?

2) Also in-order to choose the inner part of the slab, so that part is
inside the Au-Slab or the ZnO Slab?

regards


On Wed, Mar 18, 2015 at 5:02 PM, Giovanni Cantele <
giovanni.cantele at spin.cnr.it> wrote:

> The average electrostatic potential you are calculating/plotting does show
> microscopic oscillations, revealing the atomic planes
> (plot the 2d column of reference/Al100.avg.out  as a function of the 1st
> one).
>
> The calculation of the work function requires a “constant” energy level to
> compare the bulk and the slab calculation. For this purpose,
> you run a macroscopic average of the x-y averaged electrostatic potential.
> The window you choose for the macroscopic average
> is just the distance between two consecutive atomic planes (in a.u.).
> Because the input positions are in alat units, you get
>
> (2.8284271247461898 - 2.1213203435596428) * 5.4235090117 = 3.835
>
> In this way, microscopic oscillations with period 3.835 are averaged and a
> constant level (in the inner region of the slab) is obtained.
>
> Concerning 17.8087, in order to get this constant value, you can choose
> any position in the inner part of the slab where the
> macroscopic average does not show significant variations.
>
> Giovanni
>
>
> On 18 Mar 2015, at 10:49, Bipul Rakshit <bipulrr at gmail.com> wrote:
>
> In espresso, there is an example to find the workfunction of Al. In the
> run_example, the input for the the macroscopic average is the following
> cat > Al100.avg.in <http://al100.avg.in/> <<EOF
> 1
> Al100.pot
> 1.D0
> 1440
> 3
> 3.835000000
> EOF
>
> In this file the quantity "3.835" i saw in average.f90 as "awin         !
> the size of the window for macroscopic averages"
>
> So my doubt is how we can choose this no. Can we get the information from
> another file prerun file, like Al100.pot, or something else.
>
> Also in run_example there is another quantity vSlab
>
> vSlab=`grep "17.8087" Al100.avg.out | cut -d \  -f 10`
>
> So how the value correspond to "17.8087" is assign as vSlab?
>
> Kindly help me in this matter.
>
> regards
> --
> Dr. Bipul Rakshit
> Research Associate,
> Institute of Physics (IOP),
> Bhubaneswar- 751 005
> Orissa
> India
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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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-- 
Dr. Bipul Rakshit
Research Associate,
Institute of Physics (IOP),
Bhubaneswar- 751 005
Orissa
India
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