[Pw_forum] electron-phonon coupling, nesting, double-delta

[Feng, Zimin]

Hi Nicki,
 
Sorry I didn't quite follow you: as I understand - correct me if I'm wrong - what you are trying to get is a product of delta functions(?!). They don't have any relations whatsoever with electron-phonon interactions. Am I right? If you don't mind, would you like to tell me why you are tring to get this quantity?
 
The shifting of Fermi energy is done by manually adding 0.05 electrons *within the code*, rather than tot_charge - in the latter way QE calculates forces and phonons with the charged system. But the convergence with respect to smearing is done by visual examination :P - I don't yet know of something that quantifies this criterion :( 
 
you are welcome
fzm

________________________________

De : pw_forum-bounces at pwscf.org [mailto:pw_forum-bounces at pwscf.org] De la part de nicvok
Envoyé : 30 janvier 2014 05:17
À : pw_forum at pwscf.org
Objet : Re: [Pw_forum] electron-phonon coupling, nesting, double-delta



Dear Zimin, 

indeed I try to represent the q-resolved spectral function \alpha^2F(\nu,q) as eq.(3) in your paper, but 
WITHOUT the square of the interaction strength eq.(2). So what remains is the q-resolved nesting-function. 
Nevertheless, I found your paper quite interesting. How do you technically achieved the rigid-band shift? Did you add 
the additional 0.05 electrons by setting tot_charge = 0.0500000? How do you control the convergence of 
the electron-phonon parameter \Lambda or the Eliashberg function with respect to the smearing of the 
double-delta integral if you are so close to the bandedge? I would really appreciate your answers and ideas.

thanks a lot
Nicki

-------------------------------------------------------------
Nicki Frank Hinsche, Dr. rer. nat.
Institute of physics - Theoretical physics,  
Martin-Luther-University Halle-Wittenberg, 
Von-Seckendorff-Platz 1, Room 1.07 
D-06120 Halle/Saale, Germany
Tel.: ++49 345 5525460
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		Hi Nicki,
		Let me know if this is what you are trying to do:
		http://prb.aps.org/abstract/PRB/v88/i18/e184302
		fzm 
		


	-----Message d'origine-----
	De : pw_forum-bounces at pwscf.org [mailto:pw_forum-bounces at pwscf.org] De la part de nicvok
	Envoy? : 27 janvier 2014 13:28
	? : pw_forum at pwscf.org
	Objet : [Pw_forum] electron-phonon coupling, nesting, double-delta
	
	Dear all,
	
	I am trying to extract the nesting function/double delta X(q,\nu) (sim. to eq.(22)/(A1) in Wierzbowska et al. http://arxiv.org/abs/cond-mat/0504077)
	out of QE503. I would like to have it in the same way as the phonon linewidth g(q,\nu) (gamma(i,n) in matdyn.f90).
	A starting point would be gf(mu,nu,isig) in elphon.f90 and/or phase_space in elphsum_simple in elphon.f90, which should both represent the double delta by using gaussians. However, I am right now puzzled and wondering where I have to search/work for an direct output of the nesting function for arbitrary q?
	
	I would appreciate any hint.
	Nicki
	


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