Magnetic Properties
How magnetic properties are calculated on the Materials Project (MP) website.
What are magnetic properties?
The magnetic behavior of a material is a complex and rich research area. The Materials Project currently only addresses a narrow aspect of the magnetism of materials: the magnitude and ordering of atomic magnetic moments in a crystal structure, at zero temperature.
At present, Materials Project only considers collinear magnetic order which means that atomic magnetic moments are represented by scalar values and not vectors.
Methodology
The Materials Project approaches magnetism in two ways:
Historically, all materials are initialized in a ferromagnetic configuration by default. This was a pragmatic choice due to the computational expensive of considering all possible magnetic ordering. During the simulation of these materials, it is possible that the magnetic order will converge to a non-ferromagnetic order, but more likely the order will remain ferromagnetic even if the true ground state of the material is non-ferromagnetic. Therefore, the reported magnetic order for most materials on the Materials Project is a description of the calculated magnetic order, and not a prediction of the true ground state magnetic order.
For some materials, Materials Project has started to systematically search for ground state magnetic ordering of materials. This means that multiple magnetic ground states are considered for each material: ferromagnetic, anti-ferromagnetic, ferrimagnetic, etc. So far, this systematic search has been done for several thousand magnetic oxides. For these materials, the reported magnetic order is therefore a prediction of the true ground state magnetic order.
References
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