[Pw_forum] Error in routine scale_h (1)

[Alexey Akimov]

Good point, thank you! 

Alexey

----- Original Message -----
From: "Axel Kohlmeyer" <akohlmey at gmail.com>
To: "PWSCF Forum" <pw_forum at pwscf.org>
Sent: Monday, September 24, 2012 2:32:28 AM
Subject: Re: [Pw_forum] Error in routine scale_h (1)

And I venture an educated guess here, but looks toMe that you could save yourself a lot of time and effort with a small number of well picked single point calculations and thus obtained a much better initialnguess. For your system it should be easy enough to pick a cell that is a bit too large and a bit too small and a few in between. 

Variable cell calculation far from equilibrium always converge very slow. 

Axel
--
Dr. Axel Kohlmeyer  akohlmey at gmail.com  http://goo.gl/1wk0
International Centre for Theoretical Physics, Trieste. Italy.

-----Original Message-----
From: Alexey Akimov <aakimov at z.rochester.edu>
Sender: pw_forum-bounces at pwscf.org
Date: Sun, 23 Sep 2012 22:14:14 
To: PWSCF Forum<pw_forum at pwscf.org>
Reply-To: PWSCF Forum <pw_forum at pwscf.org>
Subject: Re: [Pw_forum] Error in routine scale_h (1)

I see. Thank you for the explanation!

Alexey

----- Original Message -----
From: "Stefano de Gironcoli" <degironc at sissa.it>
To: "pw forum" <pw_forum at pwscf.org>
Sent: Sunday, September 23, 2012 2:58:47 PM
Subject: Re: [Pw_forum] Error in routine scale_h (1)

as your cell shrinks the energy cutoff corresponding to your set of 
plane wave increases and it this exceeds a the maximum values in the 
precalculated psedopotential table (some 20% higher than the specified 
ecut by default if i remember correctly) the code stops. You can 
increase this limit with the cell_factor variable.

However if this keeps happening it means that your cell  was way too large !

stefano



On 09/23/2012 11:42 PM, Alexey Akimov wrote:
> my unit cell is not oscillating, but rather shrinking. shouldn't the basis size (number of plane waves) be bigger for larger cell, so the bigger cell would determine the maximal amount of memory for simulation even if the cell contracts?
>
> ----- Original Message -----
> From: "Paolo Giannozzi" <giannozz at democritos.it>
> To: "PWSCF Forum" <pw_forum at pwscf.org>
> Sent: Sunday, September 23, 2012 1:19:05 PM
> Subject: Re: [Pw_forum] Error in routine scale_h (1)
>
>
> On Sep 23, 2012, at 16:43 , Alexey Akimov wrote:
>
>> 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.
> this should not happen, unless your optimization procedure keeps
> oscillating between large and
> small volumes.
>
> P.
> ---
> Paolo Giannozzi, Dept of Chemistry&Physics&Environment,
> Univ. Udine, via delle Scienze 208, 33100 Udine, Italy
> Phone +39-0432-558216, fax +39-0432-558222
>
>
>
>
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-- 
Dr. Alexey V. Akimov

Postdoctoral Research Associate
Department of Chemistry
University of Rochester

aakimov at z.rochester.edu 
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-- 
Dr. Alexey V. Akimov

Postdoctoral Research Associate
Department of Chemistry
University of Rochester

aakimov at z.rochester.edu