EPW Forum

Hi Felix,

Thanks for pointing out. Indeed the link did not work. It has now been fixed.

Best regards,
Sabya.

Hi Liu and mxh, The system_2D in EPW 5.8 has been implemented using multiple formalisms. As already mentioned in the description of the input variables, I am mentioning it here again, the dipole_sp option will perform 2D truncation using "https://journals.aps.org/prb/abstract/10.1103/PhysRevB.107.15...

Hi Yao, Indeed, that is quite long but what I can see in your input is that you are using 128 bands. That is quite a lot!. Also, keep in mind that epw is only parallelized over the k-points. Therefore, since you have very few k-points (ignoring symmetries: 216) most of the processors are probably no...

Hi Albert,

This error has been fixed in EPW v5.8. Please download the developer version from "https://gitlab.com/epw/q-e.git".

Best regards,
Sabya.

Hi, From a first look it appears that your system where you are running EPW does not have enough memory. If it is an HPC, you can try to increase the number of nodes (while keeping the same number of cores) and see if this error goes away. Or reduce the nkf, nqf and check if it goes away. Otherwise,...

Hi,

EPW can calculate the electron-phonon interactions in all kinds of materials (of course including insulators). Therefore, it is perfectly fine to keep occupations=fixed and then use EPW to calculate the electron-phonon matrix elements.

Best regards,
Sabya.

Dear Pravin,

This problem occurs when you have more number of cores than k-points. As you said you have changed the number of nodes, how many nodes/cores you are using? Try to reduce the number of k-points and check if that works.
Otherwise, attach your input files.

Best,
Sabya.

Dear LiuHD,

For Phonon code (ph,x) related questions kindly post them to the quantum espresso forum "https://www.quantum-espresso.org/users-forum/". QE 7.2 supports PAW calculation but electron-phonon calculations have this problem.

Best,
Sabya.

Hi Muhammad, There should not be any issue with the calculation of mobility in materials with extremely high effective mass/flat-bands. Transport code implemented in EPW uses the ab-initio bandstructure (DFT or GW(if provided as .eig file) for energy eigenvalues. There is no point where "effective m...

Hi Sebastian, Thanks for the appreciation and the very nice question. Indeed, the electron-phonon matrix element is a guage dependent quantity as described in the article by Prof. Feliciano Giustino. It is true that in many formulas the electron-phonon matrix appears as |g|, however, it is a complex...