Slab calculation

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Bmodak · #1 Post by **Bmodak** » Fri Jan 24, 2014 12:41 pm

Hi I am a new user. can any body suggest me that how many number of layers I have to consider.

pavel · #2 Post by **pavel** » Fri Jan 24, 2014 3:45 pm

It depends on your task. Check how your results change with the number of layers, thickness of the gap between free surfaces and area of your surface. You can start from 6 layers and then increase the number. The gap should be about 3-4 lattice constants, otherwise your free surfaces will interact with each other due to periodical boundary conditions.

WolverBean · #3 Post by **WolverBean** » Sun Jan 26, 2014 11:08 pm

To add to what pavel said, the gap size should be about 10-12 angstrom (bigger is better but more expensive). If you want to study surface adsorption, make sure the space between slabs is big enough to accommodate your adsorbate PLUS 10-12 angstrom of empty space. Six layer slabs are good for metals (though I find that heats of adsorption are often converged after even 4 layers). For semiconductors, you may be okay with fewer layers.

Bmodak · #4 Post by **Bmodak** » Wed Jan 29, 2014 7:09 am

Thank you very much for your kind informations