convergence problem with 3d 4d transition metal

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ljzhang123
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convergence problem with 3d 4d transition metal

#1 Post by ljzhang123 » Mon Mar 28, 2016 5:05 am

Dear colleague:

when i do structure optimization for the 3d and 4d pure transition metal such as Zn with pv pesudopotential ,the electron loop couldn't convergence, can anyone help me with this problem? Thank you for your attention.

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Re: convergence problem with 3d 4d transition metal

#2 Post by admin » Mon Apr 11, 2016 2:01 pm

Can you display the problematic POSCAR?

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Re: convergence problem with 3d 4d transition metal

#3 Post by ljzhang123 » Mon Apr 11, 2016 2:10 pm

CIF file
1.0
7.9946999550 0.0000000000 0.0000000000
-3.9973499775 6.9236132567 0.0000000000
0.0000000000 0.0000000000 9.8936004639
Zn
36
Direct
0.111110002 0.222220004 0.125000000
0.222220004 0.111110002 0.375000000
0.444440007 0.222220004 0.125000000
0.555559993 0.111110002 0.375000000
0.777779996 0.222220004 0.125000000
0.888890028 0.111110002 0.375000000
0.111110002 0.555559993 0.125000000
0.222220004 0.444440007 0.375000000
0.444440007 0.555559993 0.125000000
0.555559993 0.444440007 0.375000000
0.777779996 0.555559993 0.125000000
0.888890028 0.444440007 0.375000000
0.111110002 0.888890028 0.125000000
0.222220004 0.777779996 0.375000000
0.444440007 0.888890028 0.125000000
0.555559993 0.777779996 0.375000000
0.777779996 0.888890028 0.125000000
0.888890028 0.777779996 0.375000000
0.111110002 0.222220004 0.625000000
0.222220004 0.111110002 0.875000000
0.444440007 0.222220004 0.625000000
0.555559993 0.111110002 0.875000000
0.777779996 0.222220004 0.625000000
0.888890028 0.111110002 0.875000000
0.111110002 0.555559993 0.625000000
0.222220004 0.444440007 0.875000000
0.444440007 0.555559993 0.625000000
0.555559993 0.444440007 0.875000000
0.777779996 0.555559993 0.625000000
0.888890028 0.444440007 0.875000000
0.111110002 0.888890028 0.625000000
0.222220004 0.777779996 0.875000000
0.444440007 0.888890028 0.625000000
0.555559993 0.777779996 0.875000000
0.777779996 0.888890028 0.625000000
0.888890028 0.777779996 0.875000000

This is a 3*3*2 supercell of hcp-Zn.

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Re: convergence problem with 3d 4d transition metal

#4 Post by admin » Mon Apr 11, 2016 3:34 pm

This is a numerical trap. Atoms placed in highly symmetric positions
(this is e.g. the case of pure metals, graphenes, etc.) can lead to singularities
and the numerical procedure of the electronic loop crashes.
Move the whole set of atoms slightly away from the "magic position" and the numerical
problem will disappear.

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