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> 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 > > _______________________________________________ > Pw_forum mailing list > Pw_forum at pwscf.org > http://pwscf.org/mailman/listinfo/pw_forum > -------------- next part -------------- An HTML attachment was scrubbed... URL: http://pwscf.org/pipermail/pw_forum/attachments/20140630/af69eaae/attachment.html
