[Pw_forum] Error in routine scale_h (1)

[Alexey Akimov]

Ok. I'll try this option, thank you for suggestion. In conjunction to this feature, will the memory required for calculation increase with increased cell_factor? how fast?

----- Original Message -----
From: "Martin Andersson" <ma at nano.ku.dk>
To: "PWSCF Forum" <pw_forum at pwscf.org>
Sent: Sunday, September 23, 2012 12:33:15 PM
Subject: Re: [Pw_forum] Error in routine scale_h (1)

Set cell_factor (in &cell) to a number higher than the default like 
suggested... That should work.

Cheers,
Martin Andersson
University of Copenhagen


Den 2012-09-23 4:43 PM, Alexey Akimov skrev:
> Dear all,
>
> I'm trying to optimize a relatively large system such as 2 C60 / unit cell. So i start with relatively large cell dimensions. I'm doing vc-relax calculations with either 'damp'&'damp-pr' or 'bfgs'&'bfgs' for ionic and cell dynamics options. However, after some number (~50-70) of successful  (ionic/cell) steps the calculations crash with the error:
>
>       Error in routine scale_h (1):
>       Not enough space allocated for radial FFT: try restarting with a larger cell_factor.
>
> It seems like this happens when the size of the simulation cell changes by some notable amount with respect to the starting one. Perhaps, the program automatically changes the plane wave basis set (increases). If i restart the calculations with the latest (most optimal) configuration of the system and the same amount of memory allocated, the further optimization can proceed some more time (also ~50 - 70 steps) before next crash. So in principle it is still possible to achieve the convergence with this sequence of operations, but it is quite inconvenient to reset the calculations every 50-70 steps.
>
> So my question: is there any way to avoid this and get optimized results without intermediate crashes (apart from increasing the amount of memory reserved in the beginning)?
>
> Thank you,
> Alexey
>
>

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-- 
Dr. Alexey V. Akimov

Postdoctoral Research Associate
Department of Chemistry
University of Rochester

aakimov at z.rochester.edu