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

Title: Re: [abinit-forum] shiftk for 1D crystal?

Hello Yaroslav,

For a 1D system, there is no dispersion in the other 2 directions and therefore there is no need to sample those direction and I guess that is the reason you have a sampling 114. Your 1D system is along the z-direction?

Because there is no dispersion, there is no need to shift along those directions. So you can use the shiftk 0.0 0.0 0.5 . Note that it would not matter if you had shifted the grid, but is it just more consistent. The only point that you need to be careful is for a possible Peierl’s deformation, and often you need not shift the k-points in order for this deformation to happen in DFT.

Hope this help,

Michel   


Le 26/03/06 20:04, « yshtogun@cas.usf.edu » <yshtogun@cas.usf.edu> a écrit :

> Dear abinit users!
>  I have question about shiftk. Tutorial and manual said that‰ When the primitive vectors of the lattice do NOT form a FCC or a BCC lattice, the usual (shifted) Monkhorst-Pack grids are formed by using nshiftk=1 and shiftk 0.5 0.5 0.5‰.  I tray calculate energy for my 1D crystal, I used ngkpt 1 1 4 but I am confuse about the value of shiftk. 
>   Is the value of shiftk the same for 1D crystal like for 3D? I mean can I use default value for 1D calculation. 
>
>  Thank you 
>   Yaroslav!    


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  Michel Cote                          tel: +1 (514) 343-5628     
  Professeur agrégé                   fax: +1 (514) 343-2071               
  Département de physique 
  Université de Montréal 
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  Canada                   www.phys.umontreal.ca/~michel_cote 
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