EPW Forum

Dear all,

I am dealing with the monolayer of a system for which I am interested in computing phonon self-energy for ZA phonon branch only.
I am trying to calculate phonon self-energy using EPW. I am getting linewidth of the order of
10^-13 to 10-^8 meV depending on degaussw used. I want to know what is the typical order of phonon linewidth for a semiconductor? I would be grateful for your response.



Regards,
Gautam Sharma

Dear Gautam Sharma,

It depend on the q-point you are looking at the the mode. Some mode have very strong electron-phonon coupling and some do not.

I guess phonon linewidths value for 3D semiconductors ranges from ~0 meV to ~5 meV.

Best wishes,
Samuel

Dear Sir,

Do the number I am getting are very small. I am pasting a small portion of
linewidth.phself output file (with degaussw =0.15 eV and nkf1=nkf2=50,nkf3=1).
I have 8 atoms (24 modes) in the system. Can you help me to know where things are going wrong?

# Phonon frequency and phonon lifetime in meV
# Q-point Mode Phonon freq (meV) Phonon linewidth (meV)
1 1 -0.87686329E-03 0.0000000000E+00
1 2 -0.87686322E-03 0.0000000000E+00
1 3 -0.64856015E-03 0.0000000000E+00
1 4 0.31221582E+01 0.6605622160E-15
1 5 0.32982393E+01 0.1006343510E-13
1 6 0.32982393E+01 0.1006343510E-13
1 7 0.52400905E+01 0.5236774980E-14
1 8 0.52400905E+01 0.5236774980E-14
1 9 0.54339702E+01 0.1371804353E-14
1 10 0.63100605E+01 0.1408078242E-14
1 11 0.68043927E+01 0.2818261755E-14
1 12 0.68043927E+01 0.2818261755E-14
1 13 0.82895848E+01 0.5468319569E-14
1 14 0.96703782E+01 0.3992312149E-14
1 15 0.96703782E+01 0.3992312149E-14
1 16 0.10826239E+02 0.7272394326E-14
1 17 0.10826239E+02 0.7272394326E-14
1 18 0.11903734E+02 0.4689354701E-14
1 19 0.12436377E+02 0.5633207691E-14
1 20 0.12436377E+02 0.5633207691E-14
1 21 0.12821776E+02 0.3161713992E-13
1 22 0.13910975E+02 0.5447660203E-13
1 23 0.13910975E+02 0.5447660203E-13
1 24 0.17826663E+02 0.1228592901E-11
2 1 -0.10566975E-01 0.0000000000E+00
2 2 0.10961558E+00 0.0000000000E+00
2 3 0.19247451E+00 0.0000000000E+00
2 4 0.31230680E+01 0.2419253200E-14
2 5 0.32996089E+01 0.1002007413E-13
2 6 0.32996835E+01 0.1002007413E-13
2 7 0.52375931E+01 0.5248002621E-14
2 8 0.53193011E+01 0.7994792481E-13
2 9 0.54325167E+01 0.1708062499E-14
2 10 0.63097830E+01 0.2282448072E-14
2 11 0.68011665E+01 0.2887886561E-14
2 12 0.68040719E+01 0.2887886561E-14
2 13 0.82919343E+01 0.9102404075E-14
2 14 0.96713641E+01 0.4073008090E-14
2 15 0.10826016E+02 0.7286438373E-14
2 16 0.10826508E+02 0.7286438373E-14
2 17 0.11847421E+02 0.1895147981E-11
2 18 0.11904891E+02 0.5544974136E-14
2 19 0.12436313E+02 0.5699581743E-14
2 20 0.12821113E+02 0.4092979321E-13
2 21 0.13906561E+02 0.1015910118E-12
2 22 0.13913311E+02 0.1015910118E-12
2 23 0.14810325E+02 0.2282678030E-10
2 24 0.17822299E+02 0.1242444779E-11

Dear Sir,

I have one more question related to output written in the linewidth.phself file i.e. Why there is no information related to electronic band index in the output? I checked to change the iverbosity flag, but the output is printed in the same format without any electronic information.

The phonon lifetime is by definition an integral over all electronic states (k,bands).

Also note that you need to dope your system otherwise the lifetime will be 0.

Best wishes,
Samuel

Thank you, Sir.