[Pw_forum] about neb

[Stefano Baroni]

In this way you will not obtain the normal modes of the physical system 
you are interested in, but those of a fictitious system with different 
masses. frequencies will be different, displacement patterns will be 
different.
The fact that you cannot disentangle exactly the modes in which the 
adsorbed molecule vibrates from those in which the substrate atoms 
vibrate is not an artifact of the calculation, but a fact of nature you 
have to leave with (at least if you are interested in the way Nature 
behaves rather than just in the output of a computer simulation).

best wishes,
SB

On Jun 9, 2004, at 11:27 AM, Wu Rongqin wrote:

>  
>
>  Dear Dr. Baroni,
>
>  
>
> I have thought of another way to calculate the norm mode of small 
> molecular absorbed on a surface.
>
> The idea is quite simple. Since the frequency is related closely to 
> the mass, then in the input file, I can set the mass of atoms in the 
> slab to a very large value so that the correspondent frequencies are 
> greatly lowered so the norm mode of small molecular absorbed can be 
> figured out.
>
> Just give me some comments on this and how to give a zero point energy 
> correlation
>
>   
>
> Regards
>
>  
>
> Rongqin
>
>  
>
---
Stefano Baroni    ---  SISSA  &  DEMOCRITOS National Simulation Center
via Beirut 2-4 34014 Trieste Grignano / 
[+39] 040 3787 406 (tel) -528 
(fax)

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