btw, where are old posts archived, I wanted to post these comments on Linked In Computational chemistry group to explain my reaction to a post someone else made there earlier ( see link to water model below).?
---------------------------------------- > From: marchywka at hotmail.com > To: pw_forum at pwscf.org > Date: Thu, 27 Dec 2012 11:44:44 -0500 > Subject: Re: [Pw_forum] local and global minimums in relaxation > > > > > > > Date: Mon, 24 Dec 2012 23:20:34 -0500 > > From: correlation at tut.by > > To: pw_forum at pwscf.org > > Subject: Re: [Pw_forum] local and global minimums in relaxation > > > > I see.. > > Thank you! > > Well as I understand the situation, normally you have a molecule that you > want to > optimize and hope your original structure is close enough that the "forces" > the minimizer > sees get it to the right answer. Most molecules are not in some global > minimum configuration > of atoms right? You could take atoms infinitely far apart I guess and see > what you get. > > Personally though I did have a related question and that is what is neglected > by trying to > find a static ground state and ignoring any fluctuations? This is probably > not yet > relevant compared to errors in getting static result but curious if anyone > wanted to comment. > This was just posted on the linked in Computational Chemistry group, showing importance of fluctuation in understanding water, thought it was relevant to my earlier comment LOL http://www.rsc.org/chemistryworld/2013/02/water-structure-tetrahedral-controversy-xas-xafs > > > > > > > Sergey > > > > On 12/21/2012 3:47 PM, Paolo Giannozzi wrote: > > > On Dec 21, 2012, at 20:01 , Sergey wrote: > > > > > >> when I do relaxation (using bfgs algorithm), I end up with the > > >> system in > > >> one of the minimums. It can be local one or it can be global one. And > > >> there is probably several other possible local minimums in the system. > > >> How can I publish such a result? As I see in the papers no one usually > > >> describe this issue. Usually it is just - 'we performed structural > > >> optimization (relaxation) and here is the result.' > > >> > > >> How to deal with this matter? > > > if you find a better way to deal with this matter, your future career is > > > guaranteed. It is a well-known problem. That's way smart people > > > have invented simulating annealing, genetic algorithms, > > > metadynamics, ... > > > > > > 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 > > > > > > > > > > > > > > > _______________________________________________ > > > Pw_forum mailing list > > > Pw_forum at pwscf.org > > > http://pwscf.org/mailman/listinfo/pw_forum > > > > _______________________________________________ > > Pw_forum mailing list > > Pw_forum at pwscf.org > > http://pwscf.org/mailman/listinfo/pw_forum > > _______________________________________________ > Pw_forum mailing list > Pw_forum at pwscf.org > http://pwscf.org/mailman/listinfo/pw_forum
