[Pw_forum] a not reasonable initial path for NEB calculation

[Prasenjit Ghosh]

Dear Huang,

You are the best person to guess the best initial path. What I would suggest
is to get an idea as to how the H atom diffuses (either by searching
literature or from some chemical insight) and provide the guess path by
specifying the intermediate images with the option "intermediate_image".
This way the code uses your guess path rather than doing an interpolation.

Prasenjit.

2009/3/30 lfhuang <lfhuang at theory.issp.ac.cn>

>  Dear Paolo Giannozzi and Prasenjit Ghosh:
> Thank you for your kind attention!
> I view the initial path in xcrysden, which should mean this is not related
> to the QE version (am I right?), And
> there are some C atoms even displace over several lattice constants or
> substituted by the H adatom. From other
> literatures, the H atom should diffuse along the C-C bond, based on which I
> added 3-7 intermediate images, but
> that doesn't make any different!
> Although in the first and last images, as P. Giannozzi mentioned, the C
> atoms are somewhat distorted by the
> H adatom, the displacement of them are small (less than 0.5 angstroms, the
> lattice constant is 2.5).
> So I want to ask, when you meet this kind of failure of the interpolation
> for the initial path, what would you
> do to get an reasonable one? Thanks!
>
> Best Wishes!
>
> Yours Sincerely
> L. F. Huang
>
> > Date: Sun, 29 Mar 2009 19:54:17 +0200
> > From: Paolo Giannozzi
> > Subject: Re: [Pw_forum] a not reasonable initial path for NEB
> > calculation
> > To: PWSCF Forum
> > Message-ID:
> > Content-Type: text/plain; charset="us-ascii"
> >
> >
> > On Mar 29, 2009, at 16:14 , lfhuang wrote:
> > > I am calculating the diffusion barrier of atomic H on graphene
> > > layer using NEB method. The first_image and last_image correspond
> > > to structures with a H atom on top of two nearest C atoms,
> > > respectively. However, the interpolated initial path is not
> > > reasonable that there are some largely displaced C atoms in the
> > > configurations between first and last images, because [...]
> > >
> > ...the C atom in the first and the last image were not ordered in the
> > same way.
> > > In addition, I use the QE-3.2.3 version
> > >
> > no longer supported, use it at your own risk.
> > > Could anyone help me? I'd like to appreciate any good advice!
> > >
> >
> > I think xcrysden should be able to visualize the path
> >
> > P.
> > ---
> > Paolo Giannozzi, Democritos and University of Udine, Italy
>
> > Message: 7
> > Date: Sun, 29 Mar 2009 20:49:09 +0200
> > From: Prasenjit Ghosh
> > Subject: Re: [Pw_forum] a not reasonable initial path for NEB
> > calculation
> > To: PWSCF Forum
> > Message-ID:
> >
> > Content-Type: text/plain; charset="gb2312"
> >
> > if u have some approximate idea of the path, u can provide the guess path
> by
> > mentioning the images using the option "intermediate image" in the card
> > ATOMIC_POSITIONS
> >
> > Prasenjit.
> >
>
> ------
> ======================================================================
> L.F.Huang(黄良锋) lfhuang at theory.issp.ac.cn
> ======================================================================
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> Instutue of Solid State Physics,the Chinese Academy of Sciences,
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-- 
PRASENJIT GHOSH,
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