QuantumATK Forum
QuantumATK => General Questions and Answers => Topic started by: pengdou on March 16, 2010, 09:10
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Dear everyone,
I want to relax the two-probe system like (Au wire)-(long DTB system)-(Au wire) by siesta, I don't know how to set the parameter k-sampling grid,I have a try of
%block kgrid_Monkhorst_Pack
1 0 0 0.0
0 1 0 0.0
0 0 60 0.5
%endblock kgrid_Monkhorst_Pack
but it is too slow to get the result ,so I want to know which number is enough for the k-sampling grid along z-direction?I think 60 is too big.
Thanks a lot in advance!
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For this kind of calculation setup, the more reliable solution is to do the test calculation for the convergence of fixed structure with respect to the k-point mesh, and then do the structural optimization.
You should also show us the lattice vectors of your system. Assuming the lattice vectors of your system look like the followings:
A11 A12 0
B12 B22 0
0 0 C
If the lengths of first (A11, A12, 0) and second (B12, B22, 0) lattice vectors are much shorter than the third one (0, 0, C), your setup of k-point mesh will be not suitable.
For an equivalent bulk system of two-probe system, the choice of the division number for the z direction in the k-point sampling is not same as the one for a two-probe system.
By the way, no support for the SIESTA calculations, you may post your question to here: http://www.icmab.es/siesta/Mailing-List (http://www.icmab.es/siesta/Mailing-List).
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thanks for your reply.