[QE-users] Best Strategy for Raman Mode Calculation in Magnetic Insulators Using QE

[Lorenzo Paulatto]

Hello,
Raman in metals is tricky. Also, the Raman laser resonates with the 
electrons, which means that you most likely should do it 
frequency-dependent. The best way to compute, in my opinion, is to 
compute the frequency-dependent dieletric tensor with epsil.x (requires 
a lot of empty bands to converge) and do its numerical derivative by 
finite differences along the phonon mode displacements (which you can 
get from matdyn, or just from the dynamical matrix file).
It is not very expensive, since no supercell is required. Do not forget 
to ask the experimentalist what is the energy of their laser.

hth

On 10/2/25 20:45, sdipak wrote:
>
> Dear all,
>
> I’m currently working on Raman spectra calculations for a magnetic 
> insulating material. Specifically, I’m using norm-conserving 
> pseudopotentials and nspin=2 to capture the magnetic ground state. 
> However, when I tried to do the ph.x calculation with lraman=.true., 
> it throws the following error.
>
> %%%%%%%%%%%%%%%%%%%%%%%%%%%%
>      Error in routine phq_readin (1):
>      no elec. field with metals
> %%%%%%%%%%%%%%%%%%%%%%%%%%%%
>
> Can someone recommend the workflows or strategy for Raman calculations 
> in magnetic insulators?
>
> --
> Thanks & Regards,
> Dipak Sahu
> PhD Scholar, Dept. of Physics
> Indian Institute of Technology Kanpur
>
> Contact: +91 7750055302
> Alternate email: sdipak3197 at gmail.com
>
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-- 
Dr. Lorenzo Paulatto
IR IMPMC - CNRS UMR 7590 / Sorbonne Université / MNHN
phone: +33 (0)1 442 79822 / telegram: lpaulatto
http://www.impmc.upmc.fr/~paulatto/ - https://anharmonic.github.io/
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