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transport direction for thin film
Date: 2018/04/24 15:28
Name: Prashant

Dear OpenMX Users,

I am working on metallic thin films. I am investigating transport properties of a thin film using OpenMX. The system is two-dimensional with 4nm thickness in the z direction. For this system my lattice vectors are

ax 0 0
bx by 0
0 0 cz

In this system the electrons transport is along a or b direction. Please let me know how to set the lattice vectors for lead and NEGF calculations. If I provide the lattice parameters (for lead calculations) as


ax 0 0
bx by 0
0 0 cz

the program gives me an error saying "some atomic positions overlap in the transport direction.
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Re: transport direction for thin film ( No.1 )
Date: 2018/06/11 19:25
Name: Prashant

Hi,
Does anyone have an idea how to solve the problem?
Thanks in advance.
Prashant
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Re: transport direction for thin film ( No.2 )
Date: 2018/06/11 22:51
Name: T. Ozaki

Dear Prashant,

Does your unit cell for the lead have enough thickness to ensure the conditions described
in the manual (http://www.openmx-square.org/openmx_man3.8/node116.html) as?

1. The localized basis orbitals $\phi$ in the region $C_0$ overlap with those in the regions
$L_0$ and $R_0$, but do not overlap with those in the regions $L_1$ and $R_1$.

2. The localized basis orbitals $\phi$ in the $L_i$ ($R_i$) region has no overlap with
basis orbitals in the cells beyond the nearest neighboring cells $L_{i-1}$ ($R_{i-1}$)
and $L_{i+1}$ ($R_{i+1}$).



Regards,

TO
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Re: transport direction for thin film ( No.3 )
Date: 2018/09/11 18:06
Name: Prashant  <shindepp@yahoo.com>

Dear TO,
Ya, the unit cell for the lead have enough thickness + vacuum of ~20 \AA. Still I get the same error.
Here is the input section for "Lead-Cu.dat"

NEGF.output_hks on
NEGF.filename.hks lead-copper.hks

Atoms.Number 22
Atoms.SpeciesAndCoordinates.Unit Ang # Ang|AU
<Atoms.SpeciesAndCoordinates
1 Cu 0.000000 2.203923 9.743490 5.5 5.5
2 Cu 1.272436 0.000000 9.743490 5.5 5.5
3 Cu 0.000000 0.734641 11.809480 5.5 5.5
4 Cu 1.272436 2.938564 11.809480 5.5 5.5
5 Cu 0.000000 3.673205 13.857650 5.5 5.5
6 Cu 1.272436 1.469282 13.857650 5.5 5.5
7 Cu 0.000000 2.203923 15.907550 5.5 5.5
8 Cu 1.272436 0.000000 15.907550 5.5 5.5
9 Cu 0.000000 0.734641 17.960320 5.5 5.5
10 Cu 1.272436 2.938564 17.960320 5.5 5.5
11 Cu 0.000000 3.673205 20.010290 5.5 5.5
12 Cu 1.272436 1.469282 20.010290 5.5 5.5
13 Cu 0.000000 2.203923 22.060260 5.5 5.5
14 Cu 1.272436 0.000000 22.060260 5.5 5.5
15 Cu 0.000000 0.734641 24.113000 5.5 5.5
16 Cu 1.272436 2.938564 24.113000 5.5 5.5
17 Cu 0.000000 3.673205 26.162830 5.5 5.5
18 Cu 1.272436 1.469282 26.162830 5.5 5.5
19 Cu 0.000000 2.203923 28.210930 5.5 5.5
20 Cu 1.272436 0.000000 28.210930 5.5 5.5
21 Cu 0.000000 0.734641 30.276850 5.5 5.5
22 Cu 1.272436 2.938564 30.276850 5.5 5.5
Atoms.SpeciesAndCoordinates>
Atoms.UnitVectors.Unit Ang # Ang|AU
<Atoms.UnitVectors
2.544872648 0.000000000 0.000000000
0.000000000 4.407848725 0.000000000
0.000000000 0.000000000 40.000000000
Atoms.UnitVectors>

Prashant
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Re: transport direction for thin film ( No.4 )
Date: 2018/09/14 12:57
Name: Prashant  <shindepp@yahoo.com>

Any comment about the error is appreciated.
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