Armchair Nanoribbon to CNT

[dhurba]

Hi ..In the Quantum wise Tutorial its Mentioned that ..Armchair Graphene nanoribbons shows Semiconductor property only and ziz-zag shows metallic...But I read Somewhere that semiconducting or metallic property of a Armchair nanoribbon depends on the Width of the ribbon....So that we can get a "metal" or a "semiconductor" by adjusting the width...Please help .

Another thing...Suppose we get a armchair nano-ribbon((sheet) as semiconductor by computing the band structure in VNL...Now suppose if we roll the sheet will we get a Ziz-zag carbon nano-tube with the same semiconducting property or it will be metallic and vice Versa .

So basically i want to Fully understand the relation between Graphene nano-ribbon(GNR) and Carbon Nano-tube and and how to roll and unroll them  ....and how their electronic properties affects .............


Sorry for the newbie questions but i really need to know this things ..

[Anders Blom]

Yes, the labels can be tricky.

A zigzag EDGE ribbon becomes an armchair nanotube if you roll it up, and opposite (an armchair EDGE ribbon becomes a zigzag nanotube).

Armchair EDGE nanoribbon is always semiconducting, but the gap changes with the width. You can't get a metallic armchair edge ribbon. The zigzag edge ribbons are metallic if you don't consider spin (spin opens up a gap).

Armchair nanoTUBES (n,n) are metallic. Simple tight-binding will predict zigzag tubes (n,m) with n-m=3*integer to be metallic too, but adding curvature effects will open a small band gap. So, this is consistent with the ribbons.

[dhurba]

thanks a ton