[Pw_forum] Problem during phonon calculation of bcc iron

[Krishnendu Mukherjee]

Dear Dr. Lorenzo Paulatto,

 Thank you for your reply. While learning about the Density Functional
Perturbation Theory I am practising the phonon calculation for bcc iron
with Quantum espresso 6.2. So, I need kind help from you regarding the
meaning of different parameters.

 Your reply gave me the confidence that there was no Fortran language/ or
LINUX command related problem. As per your suggestion I started to change
different parameters to make run the code till end. First of all I
decreased the values of conv_thr to 1.0e-16 and tr2_ph to 1.0e-16.

 I realized that fe.dyn1, fe.dyn2, fe.dyn3 ..... are calculated one after
another. And if in one of them if freq(1,2,3) becomes too negative the
calculation stops. Please let me know if that is the case.

 Then I checked the discussions at pw_forum and found this topic was
discussed at http://qe-forge.org/pipermail/pw_forum/2014-August/104992.html
As per the discussion when I increased the ecutrho from 200.0 to 400.0 the
code ran till end, although there were negative frequencies. So, is it true
that increasing the ecutrho helps in convergence of the code?

I have another question about the parameter mixing_beta . I did calculation
with a value of 0.2. Should I increase or decrease the value to have
positive values of frequencies.

Further I changed the K_POINTS to {automatic}  8 8 8  1 1 1. In future I
plan to change it to 12 12 12 1 1 1 and to 16 16 16 1 1 1.

Thanking you,
Yours sincerely,
Krishnendu

================================================================
Message: 12
Date: Tue, 26 Dec 2017 11:57:22 +0100
From: Lorenzo Paulatto <paulatz at gmail.com>
Subject: Re: [Pw_forum] Problem during phonon calculation of bcc iron
        ferrite
To: pw_forum at pwscf.org
Message-ID: <0f6d3673-f689-e709-b6d9-4e87649d5c1a at gmail.com>
Content-Type: text/plain; charset=utf-8; format=flowed

On 26/12/17 10:20, Krishnendu Mukherjee wrote:
> Fortran runtime error: End of file
The file fe.dyn2 is probably empty, likely because the phonon
calculation did not finish correctly.

I think you should start from scratch, paying attention to detail,
taking the necessary time to check that every step completes correctly
or understanding why it doesn't.

kind regards


--
Lorenzo Paulatto - Paris


------------------------------



-- 
Dr. Krishnendu Mukherjee,

Principal Scientist,
CSIR-NML,
Jamshedpur.
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