[QE-users] How to plot temperature dependent Phonon dispersion using Quantum Espresso

[Md. Jahid Hasan Sagor]

Hi Dear Expert,

Would someone please suggest me how can I plot temperature dependent phonon
dispersion using Quantum Espresso? The paper (10.48550/arXiv.2211.15571)
plotted phonon dispersion at different temperatures (Fig 1b) and mentioned
that

*"For phonons, we apply a Temperature Dependent Effective Potential method
(TDEP) that uses all steps in NVT simulations to construct an effective
harmonic force constants (HFCs) that can best describe the potential
landscape at certain T. This effective HFCs then intrinsically includes the
effect of anharmonic phonon-phonon interactions on the phonon frequency and
renormalize the phonon energies. Note that the structure at certain T is
the relaxed structure. Fig. 1(b) presents our calculated phonon dispersions
at a function of temperature using the effective HFCs."*

For me the procedures look difficult as I am not familiar with VASP and
AIMD. I have gone through the TDEP method (
https://tdep-developers.github.io/tdep/) where input files preparation
depends on VASP.

So, Are there any procedures I can follow to plot the temperature dependent
phonon dispersion using Quantum Espresso? I want to share one idea, please
suggest me if it looks OK to you.

   1. Run CPMD in QE (NPT ensemble) and get atomic structure at certain
   Temperature (Temp1)
   2. Relax the atoms positions (pw.x, relax.in). But the cell structure
   would not be relaxed as the structure get from CPMD simulation at the Temp1
   keep same in all of the consecutive runs.
   3. Finally, run ph.x,q2r.x and matdyn.x to get the phonon dispersion at
   the TempT1

The procedures I described above based on QE, are OK to you?

Thank you!

Best

Md J Hasan

PhD Student

Mechanical Engineering

University of Maine
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