EPW Forum

Hi, I am trying to run a direct evaluation of electron-phonon matrix elements along the
selected high-symmetry lines using density-functional perturbation theory but I am getting this error:
Error in routine read_control_ph (1): wrong elph
My ephline.in file is :
&inputph
prefix = 'XYZ'
fildvscf = 'dvscf'
ldisp = .true.
recover = .true.
fildyn = 'XYZ.dyn'
tr2_ph = 1.0d-16
qplot = .true.
q_in_band_form = .true.
electron_phonon = 'prt'
kx = 0.5
ky = 0.5
kz = 0.5
/
3
0.5000 0.0000 0.5000 20 # X
0.0000 0.0000 0.0000 20 # Gamma
0.5000 0.5000 0.5000 1 # L
I am using this command:
module load QuantumESPRESSO/7.3
mpirun -n 48 ph.x -npools 48 -i ephline.in > ephline.out
Please let me know what might be the issue.

Hi Bhawna,

The problem is with the tag electron_phonon = 'prt'. Please check the Phonon code input page https://www.quantum-espresso.org/Doc/INPUT_PH.html#idm226 for the possible options for electron-phonon tag.

Best regards,
Sabya.

Hi,
Thanks for your reply. When I use 'interpolated' tag for electron-phonon. Then, also error is coming at kx = 0.5 stating that error might be in previous line. I want to calculate the matrix elements for initial state set at "L" high symmetry point. Please let me know the proper way to perform this calculation.

Thanks,
Bhawna

Hi Bhawna,

When you specify ldisp = .true., you need to specify k-grid not a k-path.
If you want to read the "L" point coordinates, you can set ldisp = .false. and trans = .false.

regards,
Shashi

Hi Bhawna,

One more point, you need to provide the entire k-path and not just the high-symmetry points. With that 'prt' should work.

Best,
Sabya.