QuantumATK Forum

QuantumATK => General Questions and Answers => Topic started by: zhangguangping on April 15, 2016, 09:13

Title: How can we define a nonorthogonal BoxRegion ?
Post by: zhangguangping on April 15, 2016, 09:13

Dear all,

I now have been learning using the BoxRegion in ATK, which can used to simulate the gate voltage etc. However, I find the region box only can be defined to a rectangle one by specify the

Code

xmin, xmax,
ymin, ymax,
zmin, zmax

Since the lattice vector of the electrode usually not orthogonal in xy plane, such as

Code

vector_a = [8.65127, 0.0, 0.0]*Angstrom
vector_b = [-4.32564, 7.49222, 0.0]*Angstrom
vector_c = [0.0, 0.0, 7.06373620597]*Angstrom

 so a rectangle box usually does not match the unit cell in the xy plane.

Is there a method that like vector specfication to define the RegionBox which could easily solve this problem.

With best regards,

Guangping Zhang

Title: Re: How can we define a nonorthogonal BoxRegion ?
Post by: Daniele Stradi on April 15, 2016, 10:42

Dear Guangping,

in principle the fact that the a rectangle box usually does not match the unit cell in the xy plane is not a problem. You just have to ensure that the rectangle box is larger than the unit cell in the xy plane itself. See for example the tutorial:

http://quantumwise.com/publications/tutorials/item/512-opening-a-band-gap-in-silicene-and-bilayer-graphene-with-an-electric-field

The Poisson equation will be calculated taking into account only the part of the rectangle box within the unit cell.

Regards,
Daniele.

Title: Re: How can we define a nonorthogonal BoxRegion ?
Post by: zhangguangping on April 16, 2016, 04:02

Dear Daniele,

Thanks for your reply. I see your point. If the rectangle box large enough in one direction of AB plane, then the periodical boundary will extend the rectangle box to an infinite slab.

Thanks so much for your kind reply.