On Mon, Oct 23, 2017 at 3:04 PM, Jalil Mahdizadeh <[email protected] > wrote:
> What we were discusting about (solid-solid phase transition probably). > well, it depends on the specifics of the system, and whether reaxff is applicable depends on whether there is a suitable and suitably reliable parameter set. nobody but yourself or somebody working on the same kind of problem can make a definite statement. you'll have to carefully study the literature, make tests and benchmarks and also study the thermodynamics of the processes that you are modeling. none of that is specific to QE, either. i've told you about as much as somebody with a general stat mech and MD background can tell you. axel. > ------------------------------------------ > S. J. Mahdizadeh > > On Oct 23, 2017 10:29 PM, "Axel Kohlmeyer" <[email protected]> wrote: > > > > On Mon, Oct 23, 2017 at 2:58 PM, Jalil Mahdizadeh < > [email protected]> wrote: > >> Thank you Axel. Hence, I'm thinking about ReaxFF based MD instead. What >> do you think? >> > > using reaxff to do what? > > axel. > > > >> ------------------------------------------ >> S. J. Mahdizadeh >> >> On Oct 23, 2017 10:21 PM, "Axel Kohlmeyer" <[email protected]> wrote: >> >> >> >> On Mon, Oct 23, 2017 at 2:31 PM, Jalil Mahdizadeh < >> [email protected]> wrote: >> >>> Thanks god. I was thinking I'm some kind of hollow man nobody can see >>> me. However, dear axel recently a group of magicians accomplished such a >>> "doomed project" successfully. >>> >> please note that you asked about "phase transition" without any >> particular detail of what kind of transition you are after. in the most >> general case one would assume a solid-liquid or liquid-gas transition. >> those are activated processes with a significant barrier and all the issues >> i mentioned. in fact, if somebody is after determining a melting point or >> similar this way, even classical MD will fail. >> >> if you look at the transition in the paper you quote, it is a solid-solid >> transition with rather minimal changes to the geometry and probably a very >> small activation barrier, if any. yet, those folks still used a very large >> supercell. that is quite telling. >> >> at any rate, my statement, that any temperature increase will be "rapid" >> for AIMD simulations still stands. >> >> axel. >> >> >> >> >>> PHYSICAL REVIEW B 96, 054111 (2017). >>> ------------------------------------------ >>> S. J. Mahdizadeh >>> >>> On Oct 23, 2017 9:16 PM, "Axel Kohlmeyer" <[email protected]> wrote: >>> >>>> >>>> >>>> On Mon, Oct 23, 2017 at 1:04 PM, Jalil Mahdizadeh < >>>> [email protected]> wrote: >>>> >>>>> Dear QE users, >>>>>> >>>>>> I'm going to perform some vc-md with gradually heating/cooling >>>>>> process until achieving phase transition temperature. Does any body know >>>>>> how to do heating/cooling process in vc-md? I know that only "rescaling" >>>>>> option is implemented for vc-md. Could Nobody help me? >>>>>> >>>>> >>>> i suppose nobody has replied, because nobody wanted to tell you that >>>> what you are asking about, is a doomed project. >>>> >>>> at the time scales accessible to DFT based MD simulation, >>>> heating/cooling will *always* be rapid. >>>> also, it is a good idea to stay away from phase transition >>>> temperatures, since there you will have very bad sampling of phase space >>>> and suffer from massive finite size effects. >>>> >>>> axel. >>>> >>>> >>>> >>>>> >>>>>> Cheers. >>>>>> >>>>>> >>>>>> >>>>> >>>>> >>>>> >>>>> -- >>>>> S. J. Mahdizadeh >>>>> >>>>> _______________________________________________ >>>>> Pw_forum mailing list >>>>> [email protected] >>>>> http://pwscf.org/mailman/listinfo/pw_forum >>>>> >>>> >>>> >>>> >>>> -- >>>> Dr. Axel Kohlmeyer [email protected] http://goo.gl/1wk0 >>>> College of Science & Technology, Temple University, Philadelphia PA, USA >>>> International Centre for Theoretical Physics, Trieste. Italy. >>>> >>>> _______________________________________________ >>>> Pw_forum mailing list >>>> [email protected] >>>> http://pwscf.org/mailman/listinfo/pw_forum >>>> >>> >>> _______________________________________________ >>> Pw_forum mailing list >>> [email protected] >>> http://pwscf.org/mailman/listinfo/pw_forum >>> >> >> >> >> -- >> Dr. Axel Kohlmeyer [email protected] http://goo.gl/1wk0 >> College of Science & Technology, Temple University, Philadelphia PA, USA >> International Centre for Theoretical Physics, Trieste. Italy. >> >> _______________________________________________ >> Pw_forum mailing list >> [email protected] >> http://pwscf.org/mailman/listinfo/pw_forum >> >> >> >> _______________________________________________ >> Pw_forum mailing list >> [email protected] >> http://pwscf.org/mailman/listinfo/pw_forum >> > > > > -- > Dr. Axel Kohlmeyer [email protected] http://goo.gl/1wk0 > College of Science & Technology, Temple University, Philadelphia PA, USA > International Centre for Theoretical Physics, Trieste. Italy. > > _______________________________________________ > Pw_forum mailing list > [email protected] > http://pwscf.org/mailman/listinfo/pw_forum > > > > _______________________________________________ > Pw_forum mailing list > [email protected] > http://pwscf.org/mailman/listinfo/pw_forum > -- Dr. Axel Kohlmeyer [email protected] http://goo.gl/1wk0 College of Science & Technology, Temple University, Philadelphia PA, USA International Centre for Theoretical Physics, Trieste. Italy.
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