DFT-Raman Calculations for Mn-Oxide Minerals

Running Abinit Response calculations
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We are interested in calculating Raman spectra from DFT models for Mn-oxide minerals, such as MnO2 pyrolusite, but are not sure where to start. To the best of our knowledge, there have been very few DFT studies of materials with transition metals, that we think is probably due to modeling issues with non-spherical d-orbitals.

A 2010 paper (D.A. McKeown, M.I. Bell, and R. Caracas, “Theoretical Determination of the Raman Spectra of Single Crystal Forsterite (Mg2SiO4)”, American Mineralogist, v. 95, p. 980-986) calculated Raman spectra from a DFT model using Mg, Si, and oxygen spherical potentials for forsterite that agreed reasonably well with experimental data. Unfortunately, the sister calculation for the similar structure fayalite (Fe2SiO4) was a failure from what we presume to be incorrect modeling of Fe using spherical potentials.

There is a 2016 paper (Yu Meng, et al., “When Density Functional Approximations Meet Iron Oxides”, JCTC, v. 12. p. 5132-5144) where DFT models for 4 Fe-oxide minerals were calculated that had different degrees of agreement with experiment for some physical, magnetic, and electrical properties. Have there been any Raman calculations performed on these phases using these DFT models? If not, can Raman calculations be done on a-Fe2O3, for example, using these DFT approximations with ABINIT?

We are curious to see if these recent results for Fe-oxides can be applied to Mn-oxide phases.

Thank you,

David McKeown

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Hi David,

interesting topic, and abinit is definitely the right platform. wrt Razvan’s paper, you will probably need DFT+U which is implemented with PAW (not norm conserving, that’s in progress) atomic potentials. There is a corresponding tutorial

You will have to carefully consider the value of U to apply to Mn. There are many studies in the literature, so you can do some statistics and then a sweep of input files for the ground state to get the magnetic state right.
Alternatively, there is an executable to calculate U by perturbation theory ujdet

or constrained RPA

Once you have this you can run the DFPT phonons straight, I think with GGA as well, but perhaps not including SOC (works partially, under testing).

Calculations definitely exist in the literature for Fe2O3 and Cr2O3

have fun!

Matthieu

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Hello Matthieu:

          Thank you for the helpful reply. 

          As per your suggestions, we will investigate using ABINIT and  those tutorials you list.

          Can you provide the Fe2O3 and Cr2O3 references?  

          Thanks, again !

                   David
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https://journals.aps.org/prb/abstract/10.1103/PhysRevB.99.184404
one example, but there are many - google it!