[Pw_forum] Transmission calculation for simple metals

[Sclauzero Gabriele]

Dear Vladislav,

    I mostly agree with what Nicki said here below. I also believe that in your case the problem is the ewind value, which is too small and can lead to some weirdnesses in the 2D-basis set reduction. You should try at least 4.0 and check convergence as suggested by Nicki.
In my experience, the choice of epsproj depends a lot on the system. Even values around 1.d-5 could assure a decent convergence, unless the basis set reduction went bananas (e.g., because of a too small ewind).
Also, if you push epsproj very low, but you keep ewind very small, then you could also get into trouble.
In normal calculations, I never found the need to increase the nz1 from its default.

Finally, a word about the crystal structure. Are you sure that’s what you want? The neighbors of the Co atoms seem to have different bond distances. Maybe you need to choose another value for celldm(3)?

HTH


GS





Il giorno 18/lug/2014, alle ore 12:53, nicvok <nicvok at freenet.de> ha scritto:

> The parameters epsproj and ewind control the amount of basis functions  
> used in the underlying complex
> bandstructure (CBS) calculation in your case 121; cf. Choi&Ihm (http://journals.aps.org/prb/pdf/10.1103/PhysRevB.59.2267 
> ) and
> DalCorso et al. (http://journals.aps.org/prb/abstract/10.1103/PhysRevB.74.045429 
> ). So one should take a
> look at the CBS before and check for reasonableness and convergence.
> Then adapt step by step epsproj and ewind (even more nz1) and check  
> for convergence of the CBS.
> In your case ewind=2 might be okay, nevertheless I would slightly  
> increase this (3-5). Did you ever tried
> some meaningful epsproj< 1.d-7, which should be a good value? The  
> number of integral points with 22 seems to
> be okay. That it worked for other systems could be by accident. Again,  
> as always, one finds the optimal
> value of the parameters, by checking for convergence of the underlying  
> physics.
> 
> bests 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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Dr. Gabriele Sclauzero
Materials Theory - ETHZ
ETH Zurich, HIT G 43.2
Wolfgang-Pauli-Str. 27
8093 Zürich, Switzerland

Phone +41 44 633 94 10
Fax +41 44 633 14 59
gabriele.sclauzero at mat.ethz.ch
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