[Pw_forum] One minor bug, one not minor and two questions

[Stefano de Gironcoli]

in my previous  post

reminder -> remainder

stefano

On 04/11/2011 11:57 AM, Stefano de Gironcoli wrote:
> dear Laurence Marks
>
>      thank you for contributing this patch for bfgs !
>> A quick question. In the ion optimization it looks like you are
>> starting from some iterpolation of the new density (i.e. "NEW-OLD
>> atomic charge density approx. for the potential"), what is it?
> if i remember correctly the charge density of the new positions is 
> written
> as the superposition of atomic charges plus a reminder which is computed
> as the scf rho minus the superposition of atomic charges at the old 
> positions.
>
> rho_trial_new = rho_atomic_newR + (rho_scf_oldR - rho_atomic_oldR)
>
> this is done for the first ionic iteration and assumes that the main 
> change in the density is due to rigid displacement of atomic-like 
> contributions.
>
> At subsequent iterations the reminder (rho_scf_oldR-rho_atomic_oldR) 
> can be extrapolated on the basis of its change in the previous couple 
> of iterations
>
>  Stefano de Gironcoli
>
> On 04/11/2011 01:11 AM, Laurence Marks wrote:
>> For completeness, added proper comments.
>>
>> On Sun, Apr 10, 2011 at 4:13 PM, Laurence Marks
>> <L-marks at northwestern.edu>  wrote:
>>> A very minor bug that you probably known: some of the routines in
>>> S3DE/iotk/src have lines such as "# 1 "iotk_write_interf.spp" ". Most
>>> sensible preprocessors will ignore these and just give warnings.
>>>
>>> A more serious bug. Your bfgs code does not have curvature failure
>>> conditions trapped. Not to get too technical here (contact me offline
>>> if needed), unless one is close to the minimum bfgs fails unless this
>>> is done. The failure is well documented, less well known, as is the
>>> change needed (at least the standard form). I am attaching a modified
>>> version with the standard fix. It gives a slightly lower energy with
>>> smaller forces in about the same number of iterations -- due to
>>> numerical limitations I cannot compare exactly with your reference
>>> directory. I am a newbie with this code so there could be other
>>> repercussions of this change if it is used for something except
>>> optimizing the atomic positions, so perhaps a few tests are
>>> appropriate for harder problems.
>>>
>>> A quick question. In the ion optimization it looks like you are
>>> starting from some iterpolation of the new density (i.e. "NEW-OLD
>>> atomic charge density approx. for the potential"), what is it?
>>>
>>> Another quick one: line 1766 of install/configure.ac nulls out
>>> scalapack_libs and the lines below look like they are special tests,
>>> which seems to be inconsistent with line 150 and standard protocols of
>>> letting the user define input variables. (OK, while scalapack is
>>> probably only useful for large problems I might want to do some.)
>>>
>>> -- 
>>> Professor Laurence Marks
>>> Department of Materials Science and Engineering
>>> MSE Rm 2036 Cook Hall
>>> 2220 N Campus Drive
>>> Northwestern University
>>> Evanston, IL 60208, USA
>>> Tel: (847) 491-3996 Fax: (847) 491-7820
>>> email: L-marks at northwestern dot edu
>>> Web: www.numis.northwestern.edu
>>> Chair, Commission on Electron Crystallography of IUCR
>>> www.numis.northwestern.edu/
>>> Research is to see what everybody else has seen, and to think what
>>> nobody else has thought
>>> Albert Szent-Gyorgi
>>>
>>
>>
>>
>> _______________________________________________
>> Pw_forum mailing list
>> Pw_forum at pwscf.org
>> http://www.democritos.it/mailman/listinfo/pw_forum
>
>