The ABINIT Users Mailing List ( CLOSED )

[Michel Côté <michel.cote@umontreal.ca>]

Hello Paul,


Le 16/07/06 23:10, « Paul Fons » <paul-fons@aist.go.jp> a écrit :

>   I had what I hope is a easy question to answer that I hope is not too
> silly.  I have a colleague who is making metallic nanoclusters.  As I am
> ostensibly a nano-spectroscopist of a sort (x-ray absorption) I was curious 
> to
> compare structural observations of these clusters and compute some of their
> properties via first-principles calculations.  My guess is that I would have
> to put a cluster in a big box which sounds expensive from the perspective of
> plane wave code.  I was hoping to use a PAW basis to cut down on the size of
> the basis.  Any comments/suggestions?  I was also interested in the phonon
> density of states (aka the Debye Waller factor in experiment).  With a
> supercell such as this, I am not sure if it is possible (e.g. only the q=0
> point is accessible).  Am I wrong -- e.g. is there a way to calculate the
> dynamical matrix for a situation such as this?  Anyone with any examples?
> 

Putting the cluster in a big box is the way to do this type of calculations
with Abinit.

Concerning PAW, it will depend on the metal atom you are using. It might be
necessary if you are using a relative "soft" atom like Au or Ag. You will
not gain very much by doing PAW with atoms that have an energy cutoff less
than 15 Ha. Note, linear response with PAW is not yet fully implemented but
that is coming soon.

With a cluster, you only need the phonon at q=0 and Abinit can give you
those. Sorry, I not have an example at hand.

I hope this help.

Michel


> 
>  
> Paul Fons
> Senior Research Scientist
> paul-fons@aist.go.jp
> 
> Center for Applied Near-Field Optics
> National Institute of Advanced Industrial Technology
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-- 
***************************************************************
  Michel Cote                          tel: +1 (514) 343-5628
  Professeur agrégé                   fax: +1 (514) 343-2071
  Département de physique
  Université de Montréal
  C.P. 6128, succ. Centre-ville
  Montréal (Québec) H3C 3J7          Michel.Cote@umontreal.ca
  Canada                   www.phys.umontreal.ca/~michel_cote
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