EPW Forum

Dear developers and EPW users

I wanted to calculate " resistivity Vs T " as for Lead (Pd) example in documentation. I could reproduce the graph (Fig.5) for Pb as shown in the EPW website. However I have few problems to apply the given python script to my own system. I appreciate your guidance for this.

I am not clear what are below terms in the python script given by Prof. Ponce means?

Line 16 : rhoaum = 2.2999241E6 ; What this value is ?
Line 28 : a2F_tr(1) = \omega in meV from 0-10 meV ; what this does?
Line 43 : resistivity.append(196.1075/2)*(pi/T)*int*(1/rhoaum)*1E8); ; What is 196.1075/2 in this line ?

What I basically wanted to know is to identify system dependent changes needs to be done before apply this script for my system (U3Si)?


Thank you
Inoka

Dear Inoka,

If I remember correctly,
1) rhoaum is to go from atomic unit to resistivity in Ohm.
2) Just a comment. Might not be relevant
3) 196.1075 should be the volume of the primitive cell in atomic unit.

You probably only need to change the volume and the alpha_2F_tr to your system to make it work.

Best,
Samuel

Dear Dr. Ponce

Thank you for your reply.

Yes. Since Pb is fcc (4 atoms in unit cell) and celldm(1)=9.2225583816 as per the given input scf.in , 196.1075 ~ (9.2225583816^3)/4. This can be the volume of primitive unitcell.

However, I am little bit confused about how volume come to the calculation. If I am correct, this calculation is done according to the Eqn. 54 in your paper "EPW: Electron-phonon coupling, transport and superconducting properties using maximally localized Wannier functions".

If that equation is compared with line 43 in resistivity.py, only possibility is 4*electron_mass/(n * k_B* (electron_charge^2)) should give that constant ? Could you please verify this.
I couldn't find what this "n" means in the equation 54.

I am sorry that I have one more question. What are the 11 columns in a2f_tr.01 ?

I appreciate your support very much.
Have a successful year !!

Inoka

Dear S.Ponce

I tested the resistivity calculation by using the python script with Aluminum taking the unit cell volume (108.97 Bohr^3)). Its unit cell is ~ 4 Angstrom. But then the resistivity is more than twice big compare to experimental values. I am not sure why this happens. May I know how can I check where the error is ?

Thank you in Advance
Inoka