[Wien] AFM calculations for YBCO6

[delamora]

This is a problem I had studied before, but non magnetic, so I was curious to try the magnetic case; w
With YBa2Cu3O7 you have magnetism and superconductivty! braking one of Matthias rules

The result I got for, YBa2Cu3O6, was that Cu1 MM=0.0007 or "non magnetic" as far as the calculations show.
Cu2=0.5873 with U=4eV
So, you have to study only Cu2 for magnetism.
From my point of view you the most and I would guess only ordering of the inplane spins is like a chess board, alternating un and dn.
the interplanar Cu2-Cu2 ordering can be up-up or up-dn, but since there are no oxygen atoms between the planes the difference should be quite small.

I did the calculation with RxK=7 and 100 k-points with 4 parallel cores, it took half an hour.

In the supercell output you have to delete all the numbers
Ba 1 => Ba, O 1 => O and only number 1 and 2 the Cu as you want to order them
I did;
Cu 00x and 1/2,1/2,x as Cu 1 and later as 'up'
and for 0,1/2,x and 1/2,0,x as Cu 2 and later as 'dn'
Now you can have 00,-x as 'dn' and 0,1/2,-x as up and this gives another ordering
________________________________________
De: wien-bounces at zeus.theochem.tuwien.ac.at <wien-bounces at zeus.theochem.tuwien.ac.at> en nombre de Madesis Ioannis(John) <imadesis at physics.uoc.gr>
Enviado: sábado, 16 de mayo de 2015 01:09 p. m.
Para: Wien
Asunto: Re: [Wien] AFM calculations for YBCO6

Mr. Delamora, first of all thank you for your dedication, and thorough
examination of my problem.

I haven't fully tested your solution, however, there are plenty of AFM
orderings that I wish to test such as A, G and C type, all of which are
different combinations of in-plane antiferromagnetism. From first trials
of your solution, what troubles me is the fact that the
case_super.struct file does not include any numbers such as Cu1, O3.
However, I have noticed that some of the atoms have "MULT= 2" or "MULT=
4" and present additional 1 or 3 positions. So I thought of the
following:
Keep the 1 x 1 x 1 cell, for the sake of calculations, and split by
myself the Cu1 atoms from 1 atom of MULT= 4, to 2 groups of MULT= 2, and
use your solution of naming appropriately each atom. I know that you
suggested something particular, and thank you, but I need to keep the
computational cost low. Last, I change the space group to "1". After I
do what I said, I run an initialization, and a proper space group is
defined. How is that for a solution?

--
Ioannis Madesis (Μαδέσης Ιωάννης)
PhD Student
Atomic and Molecular Physics
Department of Physics
University of Crete
(0030)-210-6503598
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