Messages

1

General Questions and Answers / Re: VNL nanotube grower question

« on: September 18, 2009, 19:14 »

Thanks.

2

General Questions and Answers / VNL nanotube grower question

« on: September 18, 2009, 16:57 »

Hi all,

In Nanotube Grower, carbon nanotube period length is shown dependent on the indices and the C-C bond length. Which formula is used in this tool to calculate the period from the bond length? Could you please give the formula and a reference?

Thanks a lot,

Serhan

3

General Questions and Answers / Transmission spectrum of CNT

« on: August 24, 2009, 19:22 »

Hi all,

When I calculate the transmission spectrum of an ideal CNT for different bias voltages in ATK , I see that the transmission spectrum changes by the bias voltage a lot. Is it normal, if it is normal what is the reason of the change of transmission spectrum bu bias voltage? Any references would be appreciated.

Cheers,
Serhan

4

General Questions and Answers / Re: a question about temperature in two probe calculation

« on: August 8, 2009, 11:09 »

Thanks for the reference.

Cheers,
Serhan

5

General Questions and Answers / Re: a question about temperature in two probe calculation

« on: August 7, 2009, 21:33 »

Thanks Dr. Blom. Yes, I understand where the Landauer formula comes from and usage from some textbooks. However, I tried to ask that apart from calculating the current with the formula you've mentioned; would it be possible to include phonon effects by considering the average number of phonons in a crystal and relating its effects on the transmission of the system, T(E). Then, after modifying T(E), the Landauer formula could be again used to calculate the current. I just thought loudly, these may or may not be possible mathematically.

Or can the effects of phonons be included in a semi - emprical way

Thanks very much for your kind response again.

Cheers,
Serhan

6

General Questions and Answers / Re: a question about temperature in two probe calculation

« on: August 7, 2009, 17:29 »

Thank you very much Dr. Blom. So, is it possible to include phonon effects in the next versions of ATK?

Cheers,
Serhan

7

General Questions and Answers / Re: a question about temperature in two probe calculation

« on: August 7, 2009, 15:37 »

Hi,

The current saturates in a two-probe system as the bias voltage increases in ATK. What is the reason of this? As I understand the reason is not phonons, from this thread.

Cheers,
Serhan

8

Scripts, Tutorials and Applications / Re: Nanotube Graphene Junction

« on: August 6, 2009, 16:44 »

Hi Again,

As Dr. Blom said, the system is very complex. However, I have an idea. If you can import graphene and CNT coordinates and move the cordinates of graphene to position it under the CNT, you may obtain the geometry. For re-positioning the atoms of a configuration please consider this thread: http://quantumwise.com/forum/index.php?topic=76.0

If you do please let us to see it

Cheers,
Serhan

9

Scripts, Tutorials and Applications / Re: Nanotube Graphene Junction

« on: August 5, 2009, 22:25 »

Hi Agni. Welcome to the forum!

Could you please give a reference of the geometry, then we'd help you more.

Cheers,
Serhan

10

Scripts, Tutorials and Applications / Re: How to Import Siesta into ATK

« on: August 4, 2009, 22:29 »

Hi Suresh,

What do you mean by "interfacing" Siesta and ATK? Could you explain please?

Cheers,
Serhan

11

Scripts, Tutorials and Applications / Re: error in extraction of vnl file

« on: August 3, 2009, 08:55 »

Welcome to the forum!

When I looked at the py file, it seems that it will get input from the console, that means you have to use ATK in command window. The job manager also starts ATK, however I think it is not possible to input a filename on job manager window. So, in Windows terminal,  try please giving the command 'atk extract_transmission_from_VNL_file.py' command. Then it will run as expected.

Cheers,
Serhan

12

Scripts, Tutorials and Applications / Re: How to do I- V measurements

« on: August 1, 2009, 12:14 »

Hi premkumar85,

For each applied voltage bias, the software calculates the electron density, etc... and writes these properties to a file with an extension "nc". For each voltage different applied voltage value, the whole scf calculation must be re-calculated since the electron density in the scattering region also changes in ATK, which makes ATK a realistic calculation environment.

However, to shorten the calculation time, you can use a previously converged simulation's results (nc file) as a starting guess for the other voltage levels (of course for the same geometry). For more information please look at the manual for restoreSelfConsistentCalculation function.

Cheers,
Serhan

13

General Questions and Answers / Re: voltage sweep

« on: July 30, 2009, 20:52 »

Welcome to the forum!

Please look at this thread: http://quantumwise.com/forum/index.php?topic=19.0

Cheers,
Serhan

14

General Questions and Answers / Re: how can I get the results from the .nc file?

« on: July 27, 2009, 08:14 »

Hi,

Have you written all the current values to the vnl file? It seems you have written only the last current value. Could you send the input file, or at least the loop part if you don't want to display your geometry?

Cheers
Serhan

15

General Questions and Answers / Re: Density of states

« on: July 20, 2009, 09:03 »

Thanks, it's now Ok.

Cheers
Serhan