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

[Laurence Marks]

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
>



-- 
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
-------------- next part --------------
A non-text attachment was scrubbed...
Name: bfgs_module.f90
Type: application/octet-stream
Size: 33514 bytes
Desc: not available
URL: <http://lists.quantum-espresso.org/pipermail/users/attachments/20110410/05ccc34d/attachment.obj>