Thanks. I want to use vc-md, because it is NPT enemble. I would like to see the cell response to temperatures, e.g. . I did not find any explicit comment about the bug of temperature control. But I did see one recent message saying a very similar problem. So at this point, I am not sure whether the problem comes from the setup or from the code itself.
What I do see is the control commands are not effective at all. The tolp=10 and tolp=100 almost have the same output, e.g., which is disappointing. When tempw=100K, it did converge well, but tempw=300K can only reach 200K. And, a smaller cell seems to perform worse in temperature control. So there are a lot of phenomena. If someone is familar with this, or knows the relationship between those seemingly messy observations, please let me know. Or it is indeed the code problem, I will try to use another one. Thanks a lot ! Tian On Thu, Nov 29, 2012 at 9:49 PM, Tian Lan <tianlan at caltech.edu> wrote: > Dear all, > > I am running vc-md of a cuprite structure with 2 by 2 by 2 supercell. When > I set the tempw=300, it does converge but the equilibrium temperature seems > to be only 190K. It starts from 280 and all the way down to 190K and > converges there. Actually I did not find many controls on it, below is what > my current setups for &ions and &cells. > > I kept trying different setups, but has little effect, for example, I > tried different 'dt' from 20 to 50, different 'ion_temperature' choices, > 'tolp' or 'nraise'. I also used a primitive cell, the actual temperature > can be only 108K or so. Therefore, I am not sure whether it has something > to do with the cell size, or the temperature calibration issue, or some > setup would substantially influence the temperature control. > > &ions > tempw=300, > ion_temperature= 'rescaling', > tolp=20, > nraise=1, > pot_extrapolation='second-order', > wfc_extrapolation='second-order', > / > &cell > cell_dynamics = 'pr' , > press = 0.00 > / > Besides of it, I have a stupid question because I did not find any > information about the atom velocities. I only find updated coordinates and > forces in .out file. In .save folders, I did not find anything either. My > control icons for print are as follows: > > disk_io='high' > ! wf_collect=.TRUE. > pseudo_dir = '.', > outdir='\temp' > tstress =.true., > tprnfor =.true., > > Thank you in advance if you have any idea about these. > Best Regards, > Tian > -- > Lan, Tian > Ph.D. Candidate, Department of Applied Physics and Materials Science > California Institute of Technology, > Caltech M/C 138-78, Pasadena, CA, 91125 > -- Lan, Tian Ph.D. Candidate, Department of Applied Physics and Materials Science California Institute of Technology, Caltech M/C 138-78, Pasadena, CA, 91125 -------------- next part -------------- An HTML attachment was scrubbed... URL: http://pwscf.org/pipermail/pw_forum/attachments/20121130/ab1b3eea/attachment.html
