Messages

1

General Questions and Answers / Encountering some errors when running an ATK job

« on: October 9, 2013, 14:41 »

Hi everyone,

I am running an ATK job. However, the job terminates abnormally. The output file displays a message such as the following:

=   BAD TERMINATION OF ONE OF YOUR APPLICATION PROCESSES
=   EXIT CODE: 35072
=   CLEANING UP REMAINING PROCESSES
=   YOU CAN IGNORE THE BELOW CLEANUP MESSAGES

Can you give me some advices to solove the problem?

Thanks in advance.

2

General Questions and Answers / Re: How to get the transmission spectrum as a function of electron energy E

« on: July 26, 2013, 21:52 »

Thanks for your reply.

3

General Questions and Answers / How to get the transmission spectrum as a function of electron energy E

« on: July 25, 2013, 23:10 »

Dear all,

Can you tell me how to get the transmission spectrum as a function of electron energy E as shown in Figure enclosed.

Thanks in advance.

4

General Questions and Answers / Re: how to set the K point in the x and y direction

« on: June 18, 2013, 20:40 »

Because you are studying the CNT as electrodes, the use of 1x1 k points in x and y direction is OK.

Thanks for your reply

5

General Questions and Answers / Re: How to decide the size of the central region at the interface of the electrode

« on: June 15, 2013, 00:46 »

If depends a bit on which calculator you use, but if it's DFT it's probably not too bad. It's an approximation, but as long as all direct matrix elements are accounted for, it's probably not worse than a few other approximations made in the calculation.

Thanks. I just used the DFT to calculate the T(E).

6

General Questions and Answers / Re: How to decide the size of the central region at the interface of the electrode

« on: June 14, 2013, 21:46 »

First read http://quantumwise.com/publications/tutorials/mini-tutorials/99-how-to-set-up-the-electrodes-properly-in-a-two-probe-system. You should really set the size of the central region before using the Device from bulk tool, but I hope things are clearer after you read that page. What you probably refer to are the +- buttons at the bottom; those are only used to make the central region larger/smaller in case you need to, in order to be able to increase the electrodes.

Thanks for your reply.

I have read the page you gave. In my calculations, I just set the left(right) electrode (one primitive unit cell containing 64 atoms) length to be 6.97 A. I checked the electrode length using the script downloaded from that page and found that the truncation distance is 8.2088 Ang. It seems that 6.97 A is a litter smaller. However, if I use two primitive unit cells (the length is 6.97*2=  13.94 A) as the electrode, the system is too large to calculate.

I just want to know whether the results is not right if I just use the electrode length of 6.97 Ang.

Thanks in advance.

7

General Questions and Answers / how to set the K point in the x and y direction

« on: June 14, 2013, 21:25 »

Dear all,

I just read the topic raised by zhangguangping: http://quantumwise.com/forum/index.php?topic=2333.0#.UbtqCnjNksc. It seems that the K point in the x and y direction plays an important role in the calculation of transmission function.

So I have a question: If I calculate a two-probe CNT device which contains a scattering region consist of three CNT primitive unit cells and two (left and right) semi-infinite CNT electrodes, is it not enough accurate to set an 1*1 K point in the x and y direction? How do I set an accurate K point?

Best,

 

8

General Questions and Answers / How to decide the size of the central region at the interface of the electrode

« on: June 13, 2013, 22:12 »

Hi all,

I want to construct the two-probe device using Device from Bulk in the DEVICE TOOLS. It is easy to select the electrode lengths. However, I don't know how to selece the size of the central region at the interface of the respective electrode.

Can you give me some advices?

Thanks in advance.

Kale

9

General Questions and Answers / Re: MoS2 nanotubes

« on: May 20, 2013, 17:46 »

Thanks for raising the issue, and thanks ZH for providing the details. To be slightly more correct, the transformation is better made as

Code

     A  B  C
A':  1  1  0
B': -1  1  0
C'   0  0  1

to avoid making a left-handed cell.

We'll look into fixing the tutorial to clarify things.

It can be noted that the "A'=2A+B" version also gives an orthorhomic cell, just not aligned along the xyz axes. Another way to align the cell is therefore to use the original transformation and then go to Lattice Parameters and select "SimpleOrthorhomic" as the lattice (with "Keep Fractional coordinates"). Also, whether or not to repeat along A or B, and how to swap the axes, depends on whether you are making an armchair or zigzag tube.

Thanks

10

General Questions and Answers / Re: MoS2 nanotubes

« on: May 20, 2013, 17:45 »

Yes, it is caused by different version. In the ATK12.8.2, several parameters should be adjusted because the two primitive unit vectors in xy planes of hexagonal MoS2 are taken along the lines with an angle of +/-60 degree with respect to the X axis.

In the supercell conversion from a hexagonal primitive unit cell to an  orthorhombic supercell:
      A  B  C
A': 1   1   0
B': 1  -1   0
C'  0   0   1

In the step of repeating orthorhombic supercell, the repetition number is chosen along at the A direction with "A=20".

Additional step is needed: "Swap Axes". You may try the options  in both  the  "swap the unit cell axes" and "swap the coordinate system axes" so that the lattice parameters is the same with those shown in the video.

Thank you very much.

11

General Questions and Answers / Re: MoS2 nanotubes

« on: May 20, 2013, 08:43 »

Thanks for your reply. I am sure that I just follow the instructions and video as Nanna did. What I used is the ATK 12.8.2, while Video used the ATK 12.2. Maybe it is caused by the different version?

12

General Questions and Answers / MoS2 nanotubes

« on: May 18, 2013, 08:53 »

Dear Sir,

Now I am using the ATK 12.8.2. I want to build MoS2 nanotube, And I follow the instructions (http://www.quantumwise.com/publications/tutorials/builder/177-mos2-nanotubes). However, I can not get the MoS2 tube.

I just check my results and find that everything is good until I opened "Bulk Tools>Lattice Parameters" and selected "Cartesian" coordinates (9th step). I just find the lattice parameters in my model is different from the ones shown in the video(http://www.youtube.com/watch?v=t2_nlrW3_Qk&feature=youtu.be).

What is wrong?

Thanks in advance.

13

General Questions and Answers / Re: a tool to determine if the electrodes are long enough

« on: April 13, 2013, 09:01 »

I have solved the problem now. Thanks

14

General Questions and Answers / Re: a tool to determine if the electrodes are long enough

« on: April 12, 2013, 21:39 »

Hi, Dear Anders Blom,

Thanks for your reply. I have got the Custom Builder via Tools>Custom Builder now. However, I can not find any report in the log panel when I drop the two-probe geometry on the drop-zone labeled "Drop system here".

15

General Questions and Answers / a tool to determine if the electrodes are long enough

« on: April 12, 2013, 20:58 »

Dear Sir,

Now I am using the ATK 12.8.2. I want to use the script to determine if the electrodes are long enough before calculating the transmission spectrum. (the script I used can be found here: http://quantumwise.com/publications/tutorials/mini-tutorials/99). I droped it on the Custom builder icon in the main VNL window and then drop my two-probe geometry on the drop-zone labeled "Drop system here". However, I just find the information in the log file:

Traceback (most recent call last):
  File ".\zipdir\NL\GUI\Core\Runner.py", line 230, in run
  File ".\zipdir\NL\NanoLanguage\Builder.py", line 85, in dummyAnalyzerGenerator
NL.ComputerScienceUtilities.Exceptions.NLError: No analyzerGenerator defined. Use the method 'setAnalyzerGenerator()'
to set an analyzerGenerator

What should I do?

Thanks in advance.