Is there some references where paramagnetic unitcell is modeled using collinear antiferromagnetic ordering (for DFT)?
Dear Prasenjit Roy,
The following publication covers the answer to your question:
First-principles DFT+U modeling of actinide-based alloys: Application to paramagnetic phases of UO2 and (U,Pu) mixed oxides
Boris Dorado and Philippe Garcia
Phys. Rev. B 87, 195139 – Published 29 May 2013
ABSTRACT
We report first-principles DFT+U calculations of the paramagnetic phases of uranium dioxide (UO2) and (U,Pu) mixed oxides (MOX). We use a combination of two techniques, the first of which enables us to treat the presence of metastable states and the other the random distribution of spins (for paramagnetism) and of plutonium atoms (for MOX). The resulting method is first used to determine the ground-state properties of paramagnetic UO2 and is then applied to MOX with 12.5% and 25%Pu, for which both experimental and theoretical studies are lacking. We find the paramagnetic phase of fluorite UO2 to be more stable than the antiferromagnetic phase as expected from experimentation, with ground-state properties in excellent agreement with experimental data. Results on MOX show that most of the ground-state properties of UO2 are affected by addition of 12.5% Pu and do not seem to be much different when the plutonium content changes, at least for Pu contents below 30%. For both UO2 and MOX, it is found that the true paramagnetic order has a significant effect on the calculated elastic constants, compared to the antiferromagnetic and ferromagnetic orders. By contrast, we find that regarding energetics, the antiferromagnetic order may be used as a very good approximation of the paramagnetic state.
http://journals.aps.org/prb/abstract/10.1103/PhysRevB.87.195139
Hoping this will be helpful,
Rafik
Hi Prasenjit,
In short, yes you can. Please take a look also at this paper,
Chem. Mater., 2013, 25 (9), pp 1723–1734
DOI: 10.1021/cm400201t
Cheers,
Riza
Dear Rafik, the article you mentioned is following disordered local moment (DLM) method with non-collinear alignment of the atomic moments. Instead, I am more interested in the collinear alignment within a big supercell for modeling PM phase.
Dear Riza, I could not completely follow the content of the article. Maybe I can go to your office and ask directly.
Thanks to both of you.
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