[Pw_forum] Problem about occupation number in elph calculation

[Paolo Giannozzi]

On Thu, 2014-06-26 at 16:05 -0800, flying_lw at yeah.net wrote:

> While you say the occupation numbers are not actually used, do you
> mean that they have no effect to the integrated electron phonon
> coupling coefficient? Or you mean the contribution from the k points
> that show "NAN" occupation numbers are not counted for the integration
> over reciprocal space? 

the latter you said.

> Our Tc for MgB2 is much lower than experiment and previous QE results.
> We wonder whether the NAN error for occupation number is part of the
> reason. 

unlikely. Once again: electron-phonon coefficients calculations are
tricky

P.
> 
> Thank you again for the help. 
> 
> 
> Wei Liu
> 
> 
> 
> ______________________________________________________________________
> flying_lw at yeah.net
>          
>         From: Paolo Giannozzi
>         Date: 2014-06-25 03:20
>         To: PWSCF Forum
>         Subject: Re: [Pw_forum] Problem about occupation number in
>         elph calculation
>         I don't think that those occupation numbers are actually used.
>         If they are, you get NaN everywhere
>          
>         P.
>          
>         On Tue, 2014-06-24 at 10:10 -0800, flying_lw at yeah.net wrote:
>         > Dear Quantum Espresso users,
>         > 
>         > 
>         > I am using QE v 5.0.2 to calculate the Tc of MgB2. The job
>         is done
>         > normally, but I got one problem when  I cheked the output
>         > file mgb2.elph.out. The occupation numbers of some k points
>         are 'NaN'.
>         > I did the same job using QE v 5.1, all the 'NaN' become
>         '0.0000'. I'm
>         > not sure what is happening. Will this cause something wrong
>         in the
>         > final results?
>         > 
>         > 
>         > Part of the output file is as below:
>         > 
>         > 
>         > %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
>         > End of band structure calculation 
>         > 
>         > k = 0.0000 0.0000 0.0000 band energies (ev): 
>         > 
>         > -33.3325 -33.3325 -33.3154 -3.7339 5.7105 9.0432 9.0432
>         10.2941 
>         > 15.0631 15.0631 16.8819 
>         > 
>         > occupation numbers 
>         > 1.0000 1.0000 1.0000 1.0000 1.0000 0.0368 0.0368 -0.0001 
>         > -0.0000 -0.0000 -0.0000 
>         > 
>         > k = 0.0000 0.0000 0.1089 band energies (ev): 
>         > 
>         > -33.3324 -33.3324 -33.3165 -3.5997 4.7550 9.0927 9.0927
>         11.5641 
>         > 15.1063 15.1063 16.8566 
>         > 
>         > occupation numbers 
>         > NaN NaN NaN NaN NaN NaN NaN NaN 
>         > NaN NaN NaN 
>         > 
>         > k = 0.0000 0.0000 0.0363 band energies (ev): 
>         > 
>         > -33.3325 -33.3325 -33.3155 -3.7188 5.5783 9.0489 9.0489
>         10.4614 
>         > 15.0681 15.0681 16.8790 
>         > 
>         > occupation numbers 
>         > 1.0000 1.0000 1.0000 1.0000 1.0000 0.0333 0.0333 -0.0000 
>         > -0.0000 -0.0000 -0.0000 
>         > 
>         > k = 0.0000 0.0000 0.1451 band energies (ev): 
>         > 
>         > -33.3324 -33.3324 -33.3172 -3.4981 4.2250 9.1283 9.1283
>         12.3377 
>         > 15.1375 15.1375 16.8387 
>         > 
>         > occupation numbers 
>         > NaN NaN NaN NaN NaN NaN NaN NaN 
>         > NaN NaN NaN 
>         > 
>         > %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
>         > 
>         > 
>         > 
>         > 
>         >  I have attached the input and output files. Thank you for
>         your help.
>         > 
>         > 
>         > Best,
>         > Wei
>         > 
>         > 
>         > 
>         > 
>         > 
>         > _______________________________________________
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>          
>         -- 
>         Paolo Giannozzi, Dept. Chemistry&Physics&Environment, 
>         Univ. Udine, via delle Scienze 208, 33100 Udine, Italy
>         Phone +39-0432-558216, fax +39-0432-558222 
>          
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