[Pw_forum] about 'relax' calculation for a large job

[Paolo Giannozzi]

On Oct 29, 2007, at 15:41 , alan chen wrote:

>      I am now doing a large job of 'relax' calculation. The unit  
> cell contains 80 atoms and vacuum. The job has been running for two  
> weeks. While the total energy is decreasing,
> the amount it decreases is approximately a constant, around 0.005  
> Ry after each self-consistent calculation and the total force is  
> fluctuating around '0.02 Ry/au'. I use 'bfgs' for ion dynamics and  
> 'first extrapolation' for both pot_extrapolation and  
> wfc_extrapolation.
>      Has anyone encounted such a problem before

lots of people: it is one of the most frequently asked questions

> and how did you solve it?

search the mailing list and see here for some hints:
http://www.quantum-espresso.org/wiki/index.php/Troubleshooting_% 
28PWscf%29
item 1.28

Paolo
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Paolo Giannozzi, Dept of Physics, University of Udine
via delle Scienze 208, 33100 Udine, Italy
Phone +39-0432-558216, fax +39-0432-558222