Search found 12 matches

by hanghuichen
Thu Sep 19, 2019 3:06 am
Forum: Running the code
Topic: convergence with respect to "wscut"
Replies: 0
Views: 4964

convergence with respect to "wscut"

Dear EPW developer, When we solve the isotropic Eliashberg equation, we recently found that at a given temperature, the gap value strongly depends on the cutoff of imaginary Matsubara frequency. For a particular example, at a given temperature (T = 0.5 K), the gap is equal to 0.14 meV when "wsc...
by hanghuichen
Sun Sep 08, 2019 4:22 am
Forum: Running the code
Topic: USPP in EPW
Replies: 1
Views: 2351

USPP in EPW

Dear Roxana, I just have a quick question following the previous thread "Testing USPP vs NC: electron-phonon matrix elements". You mentioned that "I updated the USPP implementation in EPW and the corrections were made available in the QE developer branch on gitlab.". I now downlo...
by hanghuichen
Fri Jun 28, 2019 1:56 pm
Forum: Running the code
Topic: two "a2f" files
Replies: 2
Views: 3202

Re: two "a2f" files

Dear Roxana, Thank you very much indeed. I am sorry that I have been dwelling on this issue. I know the subroutine to calculate a2fij(ik,iq,ibnd,jbnd,iwph). It is a power subroutine, but it contains too much information (k- and q- dependence). Therefore I decided to implement band-resolved "a2f...
by hanghuichen
Fri Jun 28, 2019 10:30 am
Forum: Running the code
Topic: two "a2f" files
Replies: 2
Views: 3202

two "a2f" files

Dear EPW developers and EPW experts, I notice that in EPW, there are two different ways implemented to calculate "a2f" function. One is to set "eliashberg = .true." and "liso = .false. & laniso = .false.". The subroutine evaluate_a2f_lambda generates a "PREFIX....
by hanghuichen
Sun Jun 02, 2019 7:26 am
Forum: Running the code
Topic: Two-band isotropic Eliashberg equation
Replies: 2
Views: 3137

Re: Two-band isotropic Eliashberg equation

Dear Roxana,
Thank you very much.

Dr. Hanghui Chen
NYU Shanghai and New York University
by hanghuichen
Thu May 30, 2019 2:23 pm
Forum: Running the code
Topic: Two-band isotropic Eliashberg equation
Replies: 2
Views: 3137

Two-band isotropic Eliashberg equation

Dear EPW developers, I am wondering whether the current implementation of EPW enables users to solve two-band (or even multi-band) isotropic Eliashberg equation. So far if we provide a total "a2f" file, a "one-band" isotropic Eliashberg equation is solved (one Z and one Delta). I...
by hanghuichen
Wed May 29, 2019 4:48 am
Forum: Superconductivity
Topic: Degenerate bands in EPW calculations
Replies: 0
Views: 30842

Degenerate bands in EPW calculations

Dear EPW developers, The reference PRB 87, 024505 (2013) says that in the implementation of EPW, the el-ph self-energy is assumed to be diagonal in band indices. Does this approximation break down for systems with multiple-degenerate bands at the Fermi level? For example, a simple cubic perovskite o...
by hanghuichen
Sun May 12, 2019 3:16 pm
Forum: Running the code
Topic: Pade approximation
Replies: 2
Views: 2911

Re: Pade approximation

Dear Roxana,
I increase the lowest temperature and it works now.
Thank you very much for your help. I greatly appreciate that.

Dr. Hanghui Chen
New York University Shanghai and New York University
by hanghuichen
Fri May 10, 2019 8:21 am
Forum: Running the code
Topic: Pade approximation
Replies: 2
Views: 2911

Pade approximation

Dear EPW developers, I am running a calculation of isotropic Eliashberg equation + Pade approximation (given *a2f file). The calculation of isotropic Eliashberg equation is successful but the Pade approximation crashes. The error message is: Program received signal SIGSEGV: Segmentation fault - inva...
by hanghuichen
Wed Apr 24, 2019 5:48 am
Forum: Superconductivity
Topic: Superconductors with no inversion symmetry
Replies: 4
Views: 32805

Re: Superconductors with no inversion symmetry

Dear Roxana,
Thank you very much indeed. Your answer is helpful.

Dr. Hanghui Chen