[Pw_forum] Example07

[Nicola Marzari]

On 10/17/11 10:35 PM, Paolo Giannozzi wrote:
>
> On Oct 17, 2011, at 20:48 , W2AGZ wrote:
>
>> Has such a calculation of the Eliashberg parameters of aluminum
>> using QE been published
>>
> it has been done (by me: the problem was the behavior of Tc under
> pressure), but never
> published, because the result looked quite dull and did not add
> anything to previous, less sophisticated calculation. It was almost
> 10 years ago. I used something like a 24x24x24 MP
> grid (not translated) for the double-delta integration of the
> electron-phonon coefficients,
> maybe even 32x32x32. This is by far the most critical parameter.


Ciao Paolo, Paul!

Interestingly, we also have done it (i.e. Al Tc under isotropic
or isochoric strain).

We did struggle a lot to get results that were well converged
(in isochoric strain you lose a lot of symmetries), but not not
even 24x24x24 was enough to get a good convergence of T_c (i.e.
changes in broadening would affect Tc very significantly, and we
didn't have enough cpu to find the sweet spot of k-points/broadening ).


			nicola



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Prof Nicola Marzari, Chair of Theory and Simulation of Materials, EPFL