QuantumATK Forum

QuantumATK => Scripts, Tutorials and Applications => Topic started by: Nordland on January 24, 2009, 23:38

Title: Teaser: Current Density in Graphene nanoribbons.
Post by: Nordland on January 24, 2009, 23:38

Inspired by the tutorial on Graphene nanoribbons (http://quantumwise.com/publications/tutorials), I decided to try to make a module for calculating the
current density using ATK 2008.10, trying to prove that the current flows along the edges of graphene nanoribbons.

The module is almost complete, and I have done some studies on these nanoribbons, and I will post more information in the comming days, as they get in,
but just as a teaser, I present one of my first results.

A cut-plane of the current density, orthogonal on the axis of transport, for a metallic nanoribbon. The brighter the color of the cut-plane, the stronger the current density flows in this area, and judging from this, it appears that everyone is right, when they states that the current runs along the the egdes.

Title: Re: Teaser: Current Density in Graphene nanoribbons.
Post by: Nordland on January 25, 2009, 23:12

Just as I am putting my last hand on this current density module, I just wanted to share some more pictures with you, that you can generate using VNL.
I tried to take the system from the tutorial on a doped Al-wire  (Link to tutorial (http://quantumwise.com/documents/manuals/ATK-2008.10/chap.altranseigenchan.html).

What I did, was to calculate the current density through the undoped wire, and the compare it to the current density of the doped wire.

The first pictures shows the current in the undoped wire along the axis of transport, with a single cutplane orthogonal on the transport axises shown above the wire.
(http://quantumwise.com/forum/index.php?action=dlattach;topic=77.0;attach=149;image)

The second one with the wired doped with a water molecule:
(http://quantumwise.com/forum/index.php?action=dlattach;topic=77.0;attach=151;image)
Clearly as mentioned in the tutorial the doping of the Al-wire changes how the current flows through the system.

Title: Re: Teaser: Current Density in Graphene nanoribbons.
Post by: Dong on January 11, 2010, 08:18

Hi Nordland,
Good work! ;) Could you please share your script with us? :)

Title: Re: Teaser: Current Density in Graphene nanoribbons.
Post by: Nordland on January 12, 2010, 11:46

As promised, I have agreed to upload what I have done so far.

It calculates the current density for a given energy relative to the fermi level and a given k-point.
Currently there are three minor issues, that I would like to address at some stage.

• The unit shown in VNL is not the correct one.
• The plot has to be scaled in magnitude as it is currently in arbitrary unit
• Sometimes the plot looks a bit weird in the electrode.

There are some improvement that I would like, and I will make them in the order

• Perform an integral in k-space
• Perform an integral in energy space
• Calculate the current density in the XY plane as well

Please post your suggestions.

Title: Re: Teaser: Current Density in Graphene nanoribbons.
Post by: Robin on January 13, 2010, 05:07

Thanks for sharing it.