[Pw_forum] Linear response method for J

[Pietro Bonfa']

Dear Prof. Cococcioni,

this is really helpful!

Thanks for the quick answer,
kind regards,
Pietro Bonfa'

On 06/30/2014 05:31 PM, Matteo Cococcioni wrote:
> Dear Pietro,
> 
> keep in mind that the calculation of J with linear response is quite
> tricky. In fact, as we mention in the paper, it only work if you start
> from a non magnetic ground state. with a magnetic ground state, instead,
> gives quite suspicious results. the reason is, I think, that the energy
> is not variational with respect to the magnetization m.
> For CuO we only measured J from GGA as the GGA ground state is non
> magnetic.
> 
> hope this helps.
> 
> best,
> 
> Matteo
> 
> 
> On Mon, Jun 30, 2014 at 4:51 PM, Pietro Bonfa'
> <pietro.bonfa at fis.unipr.it <mailto:pietro.bonfa at fis.unipr.it>> wrote:
> 
>     Dear PWscf users,
> 
>     I'm trying to estimate J with the linear response approach discussed in
>     the article by Himmetoglu and colleagues (PRB 84, 115108 (2011) ) for a
>     T' La2CuO4 compound.
>     I already obtained a reasonable value for U and now, staring from the
>     GGA ground state, I'm perturbing onsite magnetizations.
> 
>     I get rather strange trends that you can find here (links to images at
>     the bottom of the page):
> 
>     http://pad.hdc.pw/p/EPtfu67vWX
> 
>     An example is also in attachment (I preferred not to add too many/heavy
>     attachments to the email. The above link should survive long enough and
>     contains the input and output files and other useful informations).
> 
>     Can someone give me a hint on the (in my opinion) odd results obtained
>     for atoms 10, 38, 66 and 94 (they are the atoms of the other, i.e. not
>     perturbed, antiferromagnetic sublattice in the same CuO plane).
> 
>     Should I trust the results obtained starting from those derivatives?
> 
>     Thanks in advances for your time,
>     kind regards,
>     Pietro Bonfa'
> 
>     --
>     Pietro Bonfa' - PhD student
>     Dipartimento di Fisica e Scienze della Terra "Macedonio Melloni"
>     Viale delle Scienze 7A
>     43124 Parma - Italy
> 
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-- 
Pietro Bonfa' - PhD student
Dipartimento di Fisica e Scienze della Terra "Macedonio Melloni"
Viale delle Scienze 7A
43124 Parma - Italy