[Pw_forum] one more question about NEB and CP

[vega lew]

Dear friends,

thank you for all the help.

I see arrhenius formula is suitable for my question. But I am wondering how
to determine the attempt rate for specific system?

Do you think 300K is suitable for the reaction with activation energy of 0.2
eV?

And in my case, the product state is lower than reactant state for about 0.4
eV, i.e. if the reaction happens, there is 0.6 eV barrier for
the product state to go back to the reactant state. Do you think the
dynamical equilibria of the reaction could see in some ps simulation
of pw.x?

best wishes,

vega

On Mon, Nov 23, 2009 at 6:23 AM, Nicola Marzari <marzari at mit.edu> wrote:

> vega lew wrote:
> > Dear all,
> >
> > I used to perform NEB calculations to estimate the energy barrier for
> > certain chemical reaction.
> > The calculated activation barrier is about 0.2 eV. I want the see the
> > reaction process during some pico-second of CP calculations.
> > Do you think the reaction could happen in such a short time?  and what
> > temperature is suitable for jumping over the saddle point?
> >
> > thank you for reading
> >
> > best wishes,
> >
> > vega
>
>
> Hi Vega,
>
> try to work this out by yourself, looking at the arrhenius formula ; put an
> attempt rate comparable to say an optical phonon. But the answer is
> probably yes,
> especially if you are a bit over room temperature (500-600K).
>
>                nicola
>
>
> --
> ---------------------------------------------------------------------
> Prof Nicola Marzari   Department of Materials Science and Engineering
> 13-5066   MIT   77 Massachusetts Avenue   Cambridge MA 02139-4307 USA
> tel 617.4522758 fax 2586534 marzari at mit.edu http://quasiamore.mit.edu
>
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-- 
==================================================================================
Vega Lew ( weijia liu)
Graduate student
State Key Laboratory of Materials-oriented Chemical Engineering
College of Chemistry and Chemical Engineering
Nanjing University of Technology, 210009, Nanjing, Jiangsu, China
******************************************************************************************************************
Email: vegalew at gmail.com
Office: Room A705, Technical Innovation Building, Xinmofan Road 5#, Nanjing,
Jiangsu, China
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