[QE-users] Print raw electron-phonon coupling matrix elements

[Farhat, Afifa]

Dear Developers and Users,


I am using QE to get the vibrational modes and electron-vibrational coupling matrix elements (analogue of electron-phonon coupling matrix elements) for PAH molecules (say benzene).

I used supercell and gamma only calculation. I want to print the raw electron-phonon coupling matrix elements gij-(band and mode resolved) to use them in first order correction to the wavefunction formula (equation 19), attached the link to pdf .

https://physicspages.com/pdf/Quantum%20mechanics/First%20order%20non-degenerate%20perturbation%20theory.pdf


In QE 7.1, one of the developers H.Lee has made a modified version of ph.x in the directory "test-suite/not_epw_comp", which prints the g values in standard output (for comparison with epw) as:


ibnd     jbnd     imode   enk[eV]    enk+q[eV]  omega(q)[meV]   |g|[meV]

These g values are not raw, (some square modulus thing is happening in the source code "supp.f90'), and evetually it prints absolute |g| which loose phase information.


Is there a way to get raw electron-vibrational coupling matrix elements as:


ibnd     jbnd     imode   enk[eV]    enk+q[eV]  omega(q)[meV]   Real_g [meV]  Im_g[meV]


Going to PH/elphon.f90 and modifying the source code to print the raw values has been suggested previosuly ( a thread from Fri, 14 Mar 2014), where user get errors. If someone knows how to get the raw coupling matrix elements, please reply.


Best wishes,

Afifa Farhat


Doctoral Student

Max-Planck Institute

for the Structure and Dynamics of Matter

CFEL 99 Office 02.035

Luruper Chaussee 149

22761 Hamburg

Tel: +49 (0)40 8998-88328

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