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Messages - johnnie

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General Questions and Answers / Re: Weird GNR I-V characteristic
« on: December 3, 2012, 09:15 »
Hi again and thanks for your reply.

You said that a finite bias cannot be applied to a perfectly periodic structure. However, when I apply finite bias to a perfect graphene sheet I get the resistance quantum of 6.5k using ATK as it should be. What's wrong with this?

Thanks again.

2
General Questions and Answers / Re: Weird GNR I-V characteristic
« on: December 2, 2012, 20:19 »
I understand that there's nothing new about an ideal device. But my question is: "An ideal device made of graphene sheet displays a quantum resistance of 6.5k as expected. However another ideal device made of GNR does not show this quantum resistance. Is this something about GNRs or is there a computation problem about GNRs in ATK?"

Thanks again.

3
General Questions and Answers / Re: Weird GNR I-V characteristic
« on: December 2, 2012, 13:57 »
Hi again,

When I simulate the graphene ribbon structure, I get the aformentioned weird I-V characteristic but when I simulate the same structure as a graphene sheet, the I-V characteristics is normal I mean the ballistic resistance of 6.5k exists in the ideal graphene sheet device. Is this caused from the GNR itself or a computation problem?

Regards

4
General Questions and Answers / Re: Weird GNR I-V characteristic
« on: November 30, 2012, 09:00 »
Thanks Mr. Anders, I'll have a look at that.

5
General Questions and Answers / Weird GNR I-V characteristic
« on: November 29, 2012, 14:48 »
Hello,

I am new to ATK, I used Siesta before for atomic simulations and transport simulations.

I'm trying to obtain the ideal 2-port GNR I-V characteristics using the script attached (of course by changing the bias voltage from 0V to 0.5V). Since this is an ideal device, I expect to get linear I-V characteristics  with a resistance close to resistance quantum. However, I get an alternating I-V characteristics like

V (V)     I (A)

0           0
0.1V      36.4u
0.2V      42.6u
0.3V      38.7u
0.4V      34.8u
0.5V      37.5u

My question is: what's wrong with the attached script. And second question is: can you please give an example GNR ideal 2-port device script with a linear I-V characteristics?

Best regards

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