[Pw_forum] Does considering 2*2*2 supercell is required while calculating LR U

[SRKC Sharma Yamijala]

Dear PW members,

I have gone through the tutorials of LDA+U available online (mainly of
Matteo Cococcioni and also his PRB 2005 paper). I am interested in
calculating the U for the system SrVO3 and others. If I correctly follow
the tutorial on NiO, to calculate U, I need calculate the scf with 2*2*2
supercell (and with 4*4*4 etc. till U convergence) by keeping Ni at the
origin once and by keeping O at the origin next. If I follow the above and
consider the 2*2*2 supercell then the number of atoms in my system will be
40.

But, I am guessing (I may be wrong) that supercell is considered because of
the AFM nature of NiO ground state. So, can someone please clarify whether
considering supercell is required for non-magnetic/Ferro-magnetic systems
also or not?

Thanking you for your support,
Sincerely,
Sharma.
********************************************************
*Chaitanya Sharma,*
*Prof. Pati'*s group,
Chemistry and Physics Materials unit,
JNCASR, BANGLORE,
Lab:: (080-2208) 2581, 2809
https://sites.google.com/site/sharmasrkcyamijala/
*********************************************************
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