[Pw_forum] NxNx1 k-grid for slab calculations?

[Henry J Seeley]

Nicola,

Thank you very much!

-Hank

On 2015/10/20 09:40, Nicola Marzari wrote:
> For a slab, in vacuum, there is no dispersion in the direction 
> perpendicular
> to the surface, so the NxNx1 sampling and the NxNxN sampling should be
> identical.
> (Of course the latter is N times more expensive, CPU-wise)
> 
> It they are not, it's because there is not enough vacuum.
> 
> Try it...
> 			nicola
> 
> 
> 
> On 20/10/2015 18:34, Henry J Seeley wrote:
>> Dear Users,
>> 
>> I'm doing calculations to obtain the surface energy for a variety of
>> different crystal surfaces, so I'm running both bulk and slab
>> calculations of my systems.
>> 
>> I've been under the impression that I should be using k-grids of the
>> type NxNx1 for slab calculations, according to what I've read in
>> tutorials. But I've looked in the literature, and have found people
>> using both NxNxN and NxNx1 k-grids for their calculations. Which 
>> should
>> I be using? Is an NxNxN grid not always better?
>> 
>> Thank you for your time,
>> Hank Seeley
>> Chemistry PhD student
>> University of Oregon
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