On Mon, 19 Feb 2007, Detlef Schmicker wrote: DS> Thanks a lot for the response Paolo, DS> DS> I changed DS> > > ecutwfc = 50 , DS> > > ecutrho = 300 , DS> DS> but the behaviour does not seem better.
hallo detlef, it would be easier for people that have not followed this thread all along, to quote a few more lines, so it is easier to see what this is about. DS> I calculated for 76 hours now: The total energy is 76 hrs can be a lot or little, depending on what size of a problem you have and how large/fast the machine is you're running on. i have currently a big calculation running that has been 'on the machine' for 4 weeks now and in total consumed 1.5mio CPU hours. i'm quite pleased with its progress and am optimistic it'll have advanced enough in another week or so. proper speed and time are quite relative in this business. ;-) DS> going down as expected: DS> DS> ! total energy = -1961.72747371 Ry DS> ! total energy = -1961.72856632 Ry DS> ! total energy = -1961.73085136 Ry DS> ! total energy = -1961.73414783 Ry DS> ! total energy = -1961.73790040 Ry DS> ! total energy = -1961.74093832 Ry DS> ! total energy = -1961.74316902 Ry DS> ! total energy = -1961.74619617 Ry DS> ! total energy = -1961.74717438 Ry DS> ! total energy = -1961.74824660 Ry DS> ! total energy = -1961.75286729 Ry DS> ! total energy = -1961.75525825 Ry DS> ! total energy = -1961.75771758 Ry DS> ! total energy = -1961.76046869 Ry DS> ! total energy = -1961.76271513 Ry DS> ! total energy = -1961.76306347 Ry DS> ! total energy = -1961.76500771 Ry DS> DS> DS> But the total force is not behaving as I expect it: DS> Total force = 0.023362 Total SCF DS> correction = 0.005194 DS> Total force = 0.020491 Total SCF DS> correction = 0.003656 DS> Total force = 0.022102 Total SCF DS> correction = 0.005813 DS> Total force = 0.020633 Total SCF DS> correction = 0.004226 DS> Total force = 0.020646 Total SCF DS> correction = 0.006542 DS> Total force = 0.031831 Total SCF DS> correction = 0.007696 DS> Total force = 0.047256 Total SCF DS> correction = 0.009570 DS> Total force = 0.044493 Total SCF DS> correction = 0.007352 DS> Total force = 0.079400 Total SCF DS> correction = 0.016914 DS> Total force = 0.080773 Total SCF DS> correction = 0.014257 DS> Total force = 0.044399 Total SCF DS> correction = 0.006424 DS> Total force = 0.048366 Total SCF DS> correction = 0.004975 DS> Total force = 0.046974 Total SCF DS> correction = 0.009519 DS> Total force = 0.041070 Total SCF DS> correction = 0.009807 DS> Total force = 0.049513 Total SCF DS> correction = 0.004709 DS> Total force = 0.089950 Total SCF DS> correction = 0.010658 DS> Total force = 0.074462 Total SCF DS> correction = 0.011620 DS> DS> and the stress: DS> total stress (Ry/bohr**3) DS> (kbar) P= -20.71 DS> total stress (Ry/bohr**3) DS> (kbar) P= -20.18 DS> total stress (Ry/bohr**3) DS> (kbar) P= -19.34 DS> total stress (Ry/bohr**3) DS> (kbar) P= -17.83 DS> total stress (Ry/bohr**3) DS> (kbar) P= -11.93 DS> total stress (Ry/bohr**3) DS> (kbar) P= -6.68 DS> total stress (Ry/bohr**3) DS> (kbar) P= -0.79 DS> total stress (Ry/bohr**3) DS> (kbar) P= -7.57 DS> total stress (Ry/bohr**3) DS> (kbar) P= -8.15 DS> total stress (Ry/bohr**3) DS> (kbar) P= -5.28 DS> total stress (Ry/bohr**3) DS> (kbar) P= -6.21 DS> total stress (Ry/bohr**3) DS> (kbar) P= -2.72 DS> total stress (Ry/bohr**3) DS> (kbar) P= -4.19 DS> total stress (Ry/bohr**3) DS> (kbar) P= 0.91 DS> total stress (Ry/bohr**3) DS> (kbar) P= 1.61 DS> total stress (Ry/bohr**3) DS> (kbar) P= 3.21 DS> total stress (Ry/bohr**3) DS> (kbar) P= -6.89 DS> DS> DS> and for completness I send the temperatures: DS> Ekin = 0.00000000 Ry T = 0.0 K Etot = DS> -1961.72747371 DS> Ekin = 0.00111722 Ry T = 3.8 K Etot = DS> -1961.72744910 DS> Ekin = 0.00347429 Ry T = 7.8 K Etot = DS> -1961.72737707 DS> Ekin = 0.00703939 Ry T = 13.2 K Etot = DS> -1961.72710844 DS> Ekin = 0.01110756 Ry T = 19.3 K Etot = DS> -1961.72679284 DS> Ekin = 0.01345837 Ry T = 24.6 K Etot = DS> -1961.72747996 DS> Ekin = 0.01531120 Ry T = 29.1 K Etot = DS> -1961.72785782 DS> Ekin = 0.01380786 Ry T = 31.7 K Etot = DS> -1961.73238831 DS> Ekin = 0.01215649 Ry T = 32.9 K Etot = DS> -1961.73501789 DS> Ekin = 0.01207252 Ry T = 33.8 K Etot = DS> -1961.73617409 DS> Ekin = 0.01067002 Ry T = 34.0 K Etot = DS> -1961.74219728 DS> Ekin = 0.00889187 Ry T = 33.7 K Etot = DS> -1961.74636637 DS> Ekin = 0.01081347 Ry T = 33.9 K Etot = DS> -1961.74690411 DS> Ekin = 0.01202862 Ry T = 34.5 K Etot = DS> -1961.74844007 DS> Ekin = 0.01322190 Ry T = 35.2 K Etot = DS> -1961.74949323 DS> Ekin = 0.01505569 Ry T = 36.3 K Etot = DS> -1961.74800778 DS> Ekin = 0.01128462 Ry T = 36.4 K Etot = DS> -1961.75372309 DS> well, i assume you're running damped dynamics to optimize, right? in that case it seems, that your structure is still relaxing (hence the decrease of potential energy while the kinetic energy stays on a high level). it might have helped to initialize the velocities a little bit to have the system pick up speed faster in the beginning. for as long as the potential/total energy goes down, you actually _want_ some kinetic energy in your system or else you'll be stuck in a local minimum. for as long as you have your atoms move significantly, you'll have significant total forces, the fact that stress tensor is fluctuating a lot is to be expected for a dense system. please note, that you can figure out the proper values for ecutwfc and ecutrho with single point calculations (just enable printing of forces and stress). most uspps work quite accurate for ecutwfc 30ry to 50ry, a choice of 35-40ry is usually conservative, however to converge the stress tensor well (especially for GGA functionals) you may need a 6 to 10 times higher density cutoff. once you have those converged to an accuracy that you are comfortable with, you can start the relaxation. it might be more efficient to start the relaxation with less accurate choice of parameters and then crank them up when you're getting close to the minimum. DS> I tried several values for dt (50 -- 300) and did the DS> calculation with lower there are a bunch of strategies to make vc-relax work efficiently, e.g. use the same mass for all atoms. the value of dt has to be chosen to integrate the equations of motions in that case correctly, i.e. it is usually determined by the smallest mass in the system. note that also the fictitious mass for the cell dynamics is related to that. check out the material at. http://www.vlab.msi.umn.edu/events/lecture.shtml DS> ecutwfc = 30 , ecutrho = 120 , DS> in the last weeks. I also calculated 5 times longer DS> than the actual 78 hours, but nothing changed the DS> behaviour, that the total force is not going down DS> below approx. 0.02 DS> DS> Perhaps somebody can help. DS> DS> Thanks a lot, Detlef DS> DS> P.S.: I have strong evidence for unusual mail problem DS> with the list :-) you have to make certain, that you always use the correct sender address (not only the from line) which has to be the one you are subscribed with. there are hundreds of people on this list that have no problem. most reported problems with mailing lists, where you have to be subscribed to be able to post are related to this. these days also a lot of mailing list mails are 'eaten' by overly eager spam filters (since mailing lists are essentially using a similar distribution mechanism as most spam does). gruessle, axel. DS> DS> --- Paolo Giannozzi <giannozz at nest.sns.it> schrieb: DS> DS> > DS> > On Feb 15, 2007, at 18:23 , Detlef Schmicker wrote: DS> > DS> > > (In case an list administrator reads this, I can DS> > send the DS> > > error messages to him). DS> > DS> > unless you have solid evidence that it is not the DS> > usual DS> > problem (i.e. e-mail mismatch), please don't waste DS> > your DS> > time and mine DS> > DS> > > ecutwfc = 50 , DS> > > ecutrho = 190 , DS> > DS> > not good: for USPP, ecutrho should be larger than DS> > 4*ecutwfc DS> > DS> > Paolo DS> > --- DS> > Paolo Giannozzi, Democritos and University of Udine, DS> > Italy DS> > DS> > DS> > _______________________________________________ DS> > Pw_forum mailing list DS> > Pw_forum at pwscf.org DS> > http://www.democritos.it/mailman/listinfo/pw_forum DS> > DS> DS> DS> DS> DS> DS> DS> DS> ___________________________________________________________ DS> Der fr?he Vogel f?ngt den Wurm. Hier gelangen Sie zum neuen Yahoo! Mail: http://mail.yahoo.de DS> _______________________________________________ DS> Pw_forum mailing list DS> Pw_forum at pwscf.org DS> http://www.democritos.it/mailman/listinfo/pw_forum DS> -- ======================================================================= Axel Kohlmeyer akohlmey at cmm.chem.upenn.edu http://www.cmm.upenn.edu Center for Molecular Modeling -- University of Pennsylvania Department of Chemistry, 231 S.34th Street, Philadelphia, PA 19104-6323 tel: 1-215-898-1582, fax: 1-215-573-6233, office-tel: 1-215-898-5425 ======================================================================= If you make something idiot-proof, the universe creates a better idiot.
