It has been there for some time, didn't seem to have any relevant effect. do you have evidence of the contrary? stefano
On 04/11/2011 05:25 PM, Laurence Marks wrote: > Thanks. > > Another question if I may. From the looks of PW/mix_rho.f90 you do not > use the weights in the Johnson paper, just a straight inverse of > betamix (what would be called Y^T Y in the optimization literature) at > lines 289-295? Have you considered a regularization, e.g. adding after > line 278 something like > > betamix(i,i)=betamix(i,i) + 1.D-7/iter_used > > which is about right for your Al (001) example. The regularization > term (e.g. PRB 78, 075114 (2008)) is a bit empirical, although I might > be able to change this. > > This is safe, so long as mix_rho.f90 is only used for mixing densities > during the scf iterations -- is it used elsewhere? > > On Mon, Apr 11, 2011 at 5:12 AM, Stefano de Gironcoli<degironc at sissa.it> > wrote: >> 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 >>> >> _______________________________________________ >> Pw_forum mailing list >> Pw_forum at pwscf.org >> http://www.democritos.it/mailman/listinfo/pw_forum >> > >
