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Use of symmetry in Openmx
Date: 2011/07/22 18:32
Name: Mauro Sgroi   <>

Dear all,
I'd like to understand how symmetry is used in the code. If I calculate a band structure of a compound like LiFePO4, which has an orthorhombic Pmnb space group and 28 atoms in the unit cell, I don't obtain degenerate bands in accordance to symmetry but many energy levels slightly displaced along the energy axis.
It seems to me that the code doesn't treat symmetry related atoms as equivalent.
How can I recover the correct description of the system?

Thanks a lot and best regards,
Mauro Sgroi.
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Re: Use of symmetry in Openmx ( No.1 )
Date: 2011/07/22 22:16
Name: T.Ozaki


The regular mesh OpenMX uses breaks the original symmetry of system.
The only way to recover the symmetry is to increase the cutoff energy
by the keyword, scf.energycutoff. For such a case, we generally use a high
cutoff energy such as 400-500 Ryd, while a large amount of memory is required.

Could you try to use a higher cutoff energy, and see what happens?


Re: Use of symmetry in Openmx ( No.2 )
Date: 2011/07/22 22:46
Name: Mauro Sgroi  <>

for sure I will try. Now I' out of office for a conference. Next week I will post the results of the tests.
Thanks a lot for the information.
Kind regards,

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