How to select N1,N2,N3 in k-point file.

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shyam
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How to select N1,N2,N3 in k-point file.

#1 Post by shyam » Mon Dec 23, 2013 7:41 am

Dear sir,
I want to have a k-spacing of 0.12/angstorm in my mesh. I have a lattice having a=5.10540
b=11.96880
c=5.94120
Alpha=90
Beta=121.2840
Gamma=90
With this information i want to calculate those three numbers for monkhorst pack with k spacing as above spacified 0.12/angstorm.
I am searching for softwares but failed till now.
Please help.
Last edited by shyam on Mon Dec 23, 2013 7:41 am, edited 1 time in total.

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How to select N1,N2,N3 in k-point file.

#2 Post by admin » Mon Dec 23, 2013 2:03 pm

When you use 2 1 2 you have 0.10, 0.08, 0.08 sampling of the k-space.
Last edited by admin on Mon Dec 23, 2013 2:03 pm, edited 1 time in total.

shyam
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How to select N1,N2,N3 in k-point file.

#3 Post by shyam » Mon Dec 23, 2013 2:34 pm

Dear sir,
I want to know general procedure that I can help to others also. I tried this manually for cubic systems. I convert lattice constants into reciprocal lattice constants and then divide by 0.12 to get N1,N2,N3.But this is a complex procedure for crystals other than cubic. This can be done by medeA vasp. But I need a free software. Can you please help me in this case.
Last edited by shyam on Mon Dec 23, 2013 2:34 pm, edited 1 time in total.

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eariel
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How to select N1,N2,N3 in k-point file.

#4 Post by eariel » Mon Dec 23, 2013 2:42 pm

Just use the keyword KSPACING
Last edited by eariel on Mon Dec 23, 2013 2:42 pm, edited 1 time in total.

shyam
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How to select N1,N2,N3 in k-point file.

#5 Post by shyam » Mon Dec 23, 2013 3:32 pm

Dear eariel,
Thank you very much for solving my problem. I was focusing totally on making K-points file and was not aware of this type of solution.
Last edited by shyam on Mon Dec 23, 2013 3:32 pm, edited 1 time in total.

shyam
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How to select N1,N2,N3 in k-point file.

#6 Post by shyam » Mon Dec 23, 2013 3:55 pm

One more query i have if you can please solve,
If i have to simulate a surface with vasp then i use N=1 for that particular dimension in kpoint file. How can i use kspacing tag with the surfaces.
Last edited by shyam on Mon Dec 23, 2013 3:55 pm, edited 1 time in total.

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How to select N1,N2,N3 in k-point file.

#7 Post by eariel » Tue Jan 07, 2014 11:35 am

Probably you have already found the answer. For a surface, you need to use a supercell large enough in the perpendicular direction. If the supercell is large enough, KSPACING will set N=1 in that direction.
If you need a very dense k-point (a low KSPACING), you may not afford to build a sufficiently long supercell. In this case do

grep generate OUTCAR

and you will know the N1 N2 N3 set by vasp. Use these values to set KPOINTS.
Regards
Eduardo
Last edited by eariel on Tue Jan 07, 2014 11:35 am, edited 1 time in total.

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