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 > >
