[Pw_forum] Query regarding Al2O3 system slab calculation

Ngoc Linh Nguyen nnlinh at sissa.it
Wed Jun 2 11:07:16 CEST 2010

Vikas Varshney wrote:
> Dear All,
> My final motivation is to simulate adsorption of several small 
> molecules on Al2O3 slab. The strategy I am undertaking (and hence I 
> have few questions) is below. Please correct me if I am wrong at any 
> stage of my calculation.
> I want to get the ground state of the Al2O3 slab. In this regard, I 
> got the unit cell of Al2O3 which is trigonal ( Space group R-3c, point 
> group D3d, 30 atoms) . This is not the primitive unit cell (which is 
> rhombhohedral and contain 10 atoms). The reason is to eventually 
> simulate 0 0 1 surface. It seems that the structure consist of 2 basis 
> atoms. The rest are defined by different symmetry operations for the 
> point group of Al2O3.
> Is is possible to make use of symmetry operations and run the 
> calculation on unit cell of Al2O3 by specifying only two basis atoms 
> and then run slab calculation with 30 atoms? Or should I just create 
> a 30 atom unit cell with vacuum along Z direction in a slab geometry 
> and relax it? 
I am not clear about your question much.
Anyway, I do the simulation of adsorption on the slab by form a 
supercell that stores the substrate + vacuum + adsorbate atoms.
You can see in previous archives to understand how to form a supercell.




> Best Regards,
> Vikas
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 Nguyen Ngoc Linh, PhD Student
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