EPW Forum

Dear all, Recently, I am trying to calculate the el-ph coupling in high-temperature HfB2. The scf and nscf calculations are all right but there is something wrong with the calculated lambda and gamma at specific q points. The lambda can be large as well as 50 and the gamma is almost 30 meV at some ...

Dear EPW Developers and Users, Recently, I am calculating the electron-phonon coupling in the 2D MoS2. Following the posts in the EPW forum, I have prepared the input file of epw and calculate the electron-phonon coupling using the EPW-4.1. However, the calculated value is far too large, just like ...

Dear all users, Recently, I am computing the temperature influence on electron-phonon coupling in the example of GaN. However, when I increase the temperature (eptemp), the electron-phonon coupling constant increase to very large values (>20000). It seems unphysical. So what should I do? In your way ...

[code]Dear Carla, Thanks very much for your explanation of Fermi energy used in EPW. Following the idea, I try to correlate the doping concentration with the Fermi level in the example of GaN. After the scf calculation, I have obtained the highest occupation level (that is Fermi level) of 10.952293 ...

Dear Samuel,

In some situations, I have to increase the value of fsthick. For example, the doping will shift the Fermi level upwards or downwards. If the fsthick is too small, I will get the zero lamda.

Best

Jiayue

Dear Samuel,

What's the detailed meaning of fsthick? Does it means that the electron-phonon interaction within the fermi surface should be zero, or what else?
In the calculation, what rules we should follow to set the value of fsthick?

Best

Jiayue
RWTH Aachen University, Germany

Dear all EPW users, Recently, I am puzzled with the definition of Fermi energy in the input file of epw.in. According to the wikipedia, the Fermi energy is the energy difference between the highest and lowest occupation states of single-particle. And its definition needs one reference. So there ...

Dear Carla, Thanks for your advice and I have read the linked paper. It does a great favor. Yet I have another problem on how to simulate the doping in EPW. Should we just assume that the doping only affects the Fermi energy, or should use the virtual crystal approximation to build the doped ...

Dear all users, Recently, I have ran the GaN example and successfully obtained the phonon linewidth by setting the parameter phselfen and a2f to be true. However, when I draw the phonon dispersion curve, I find that the phonon self_energy of the 12nd optical branch is very large, to be 10^4. I want ...

Dear Samuel, Thanks for your reply. I have checked the igk files and there are 48 such files named upto gan.igk48 (since I use the npool of 48). Besides, I change nothing on the input file of scf.in, nscf.in and epw.in. Have compared the output files of phonons for gan where were performed on two ...