[Pw_forum] Relax calculation in quantum espresso with 56 atoms had not been converged

[Michael Sullivan]

You may have set nstep to 40. If you are using BFGS, it could be that it actually took 50 steps (the default, I think) but it only used the last 39 steps. Have a look at the energies and see how it looks by using a grep command like this:
grep "!    total energy " <YOUR OUTPUT FILE>

If you add -c to grep then it should give you the number of optimization steps it took.

If this isn't the case, then you'll need to share more information and it could be an issue with your computer.

Mike
michael at ihpc.a-star.edu.sg
http://www.sullivan.sg/

From: pw_forum-bounces at pwscf.org [mailto:pw_forum-bounces at pwscf.org] On Behalf Of Shaptrishi Sharma
Sent: Wednesday, August 19, 2009 9:55 PM
To: pw_forum at pwscf.org
Subject: Re: [Pw_forum] Pw_forum Digest, Vol 26, Issue 52

Hi Mike,

Thansk for your help, well I cannot understand your this point "Only allowed 40 optimization steps." How do we know that the optimisation steps are 40 and why??

Thanks

SS
My two guesses are:

(1) Ran out of time in the queue.
(2) Only allowed 40 optimization steps.

That said, we need more information. Usually something will show up in the error file that will give us a hint.

Mike
michael at ihpc.a-star.edu.sg
http://www.sullivan.sg/

From: pw_forum-bounces at pwscf.org [mailto:pw_forum-bounces at pwscf.org] On Behalf Of Shaptrishi Sharma
Sent: Wednesday, August 19, 2009 5:13 PM
To: pw_forum at pwscf.org
Subject: [Pw_forum] Relax calculation in quantum espresso with 56 atoms had not been converged

Hi ,

I have submitted one relax calculation for 56 atoms in quantum espresso , however after 39 iterations it stops without any further informations, nor even a CRASH file. So any body can suggest me what the possible reason?

Thanks
SS

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