Re: How to apply periodic boundary conditions ( No.1 ) 
 Date: 2019/01/18 01:25
 Name: Naoya Yamaguchi
 Hi,
OpenMX always considers periodic boundary conditions along a, b, and caxes except some methods, such as NEGF and ESM. For example, slab calculations are usually performed by inserting a vacuum region with an enough width to remove influence of image cells through "Atoms.UnitVectors" as you said.
Regards, Naoya Yamaguchi

Re: How to apply periodic boundary conditions ( No.2 ) 
 Date: 2019/01/18 13:53
 Name: sanjeev
Dear Yamaguchi,
Thank you very much for your reply. But still my doubt is not clear. In the above mentioned paper the author has mentioned that he made Y & Z directions nonperiodic. My question is that, How he made Y & Z nonperiodic and X as periodic. while, openmx consider all x,y,z directions as periodic.
Now suppose I want to simulate graphene fragments with a supercell dimensions x= 10, y=50, z=50, for this I set.
<Atoms.UnitVectors 10.000 0.000 0.000 0.000 50.000 0.000 0.000 0.000 50.000 Atoms.UnitVectors>
it means I have created a vacuum in Y & Z directions, but how it mean that my calculations is periodic in x direction only.
It is right if I say that my calculations are periodic in all x,y,z directions
Thanking in advance.
Sanjeev

Re: How to apply periodic boundary conditions ( No.3 ) 
 Date: 2019/01/19 02:01
 Name: Naoya Yamaguchi
 Dear Sanjeev,
>My question is that, How he made Y & Z nonperiodic and X as periodic. while, openmx consider all x,y,z >directions as periodic.
Now I read the paper and I guess that they did band calculations using OpenMX 3.4 (or 3.5) and inserted a vacuum region, for example: Atoms.UnitVectors.Unit Ang <Atoms.UnitVectors 3.11 0.0 0.0 0.0 L 0.0 0.0 0.0 L Atoms.UnitVectors> , where L>20.
>Now suppose I want to simulate graphene fragments with a supercell dimensions >x= 10, y=50, z=50, for this I set.
I think it is right for calculations of onedimensional materials such as nanoribbons.
Regards, Naoya Yamaguchi

Re: How to apply periodic boundary conditions ( No.4 ) 
 Date: 2019/02/08 23:03
 Name: Kylin <Kylincaster@foxmail.com>
 Dear all,
The periodicity in OpenMX calculation is automatically determined and straightforwardly shown in the screen log files as "The system is moleculechainslabbulk" will be displayed as in the screen log file, representing 0D1D2D and 3D system respectively. So be careful to check periodicity in our calculation which was determined by PAOs cutoff (Rc) and dimensions of box sizes. It becomes nonperiodic only with 2Rc > box_size.
Moreover, the calculation of Uele was based on FFT which is only valid for 3D periodicity box which may induce some problems with the low dimensional material studies. So a large interlayer vacuum spacing is necessary or taking the effective screening medium (ESM) method
Cheers,
Kylin

