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General Questions and Answers / Re: Help! Can't get magnetoresistance ratio
« on: September 1, 2010, 04:05 »
Is there any other method to calculate the MR for my system using atk?
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General Questions and Answers / Help! Can't get magnetoresistance ratio
« on: August 31, 2010, 16:04 »
Dear everyone,
I can't calculate the magnetoresistance ratio (MR) for my two-probe system. I noticed that there several papers that calculate MR using atk, such as [PhysRevB.81.233403], [APPLIED PHYSICS LETTERS 96, 042104], [PhysRevB.78.224418] ... (you can search 'magnetoresistance' in the publication list of atk). These papers use the same method, calculating the currents/transmissions by seting the electrodes to be spin parallel (P) and antiparallel (AP). Also, there are similiar examples in the manuals/tutorials, like 'Mini-tutorial 2' in http://www.quantumwise.com/documents/tutorials/UpgradeGuide_10.8/XHTML/ .
My two-probe is similar to this 'Mini-tutorial 2'. I also use the atomic carbon linear chain as the electrode, but the bond distance is 1.27 angstrom (I get this value by minimizing the total energy and it also can be found in published papers), not 2.90 angstrom in the tutorial.
The problem is, I can only set the initial spin polarized states of electrodes to be P or AP. After scf steps, they (P and AP) both converged to a unpolarized state. SO I can't get the currents/transmissions for P and AP.
Are there any other methods?
Can anyone help me?
Thank you!
I can't calculate the magnetoresistance ratio (MR) for my two-probe system. I noticed that there several papers that calculate MR using atk, such as [PhysRevB.81.233403], [APPLIED PHYSICS LETTERS 96, 042104], [PhysRevB.78.224418] ... (you can search 'magnetoresistance' in the publication list of atk). These papers use the same method, calculating the currents/transmissions by seting the electrodes to be spin parallel (P) and antiparallel (AP). Also, there are similiar examples in the manuals/tutorials, like 'Mini-tutorial 2' in http://www.quantumwise.com/documents/tutorials/UpgradeGuide_10.8/XHTML/ .
My two-probe is similar to this 'Mini-tutorial 2'. I also use the atomic carbon linear chain as the electrode, but the bond distance is 1.27 angstrom (I get this value by minimizing the total energy and it also can be found in published papers), not 2.90 angstrom in the tutorial.
The problem is, I can only set the initial spin polarized states of electrodes to be P or AP. After scf steps, they (P and AP) both converged to a unpolarized state. SO I can't get the currents/transmissions for P and AP.
Are there any other methods?
Can anyone help me?
Thank you!
3
Installation and License Questions / Re: error happend when install
« on: August 30, 2010, 12:23 »
Forget onething--thank you!
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Installation and License Questions / Re: error happend when install
« on: August 30, 2010, 12:21 »
I have fixed it. 
Another user has set something in the system before.
Another user has set something in the system before.
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Installation and License Questions / Re: error happend when install
« on: August 30, 2010, 06:01 »
Dear everyone,
I encountered the same error. And I have tried both the methods of Norland and Anders Blom, but still can't work.
Could anyone give me some other methods?
Thank you!
I encountered the same error. And I have tried both the methods of Norland and Anders Blom, but still can't work.
Could anyone give me some other methods?
Thank you!
6
Scripts, Tutorials and Applications / Re: Teaser: Current Density in Graphene nanoribbons.
« on: January 11, 2010, 08:18 »
Hi Nordland,
Good work! Could you please share your script with us?
Good work!
Could you please share your script with us?
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General Questions and Answers / Re: How to deal with the strange voltage drop?
« on: April 15, 2009, 02:52 »
Thank you, Nordland!
I calculated it again and used the new constraint DensityMatrix method. This time it looks correct.
I calculated it again and used the new constraint DensityMatrix method. This time it looks correct.
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General Questions and Answers / How to deal with the strange voltage drop?
« on: April 14, 2009, 04:18 »
Hi, everyone!
I get a strange voltage drop image (0.2V - 0.0V). There're abrupt changes in the right electrode, but none in the left. What confuses me is that, there are more layers in the right than in the left. How to solve it? Should I add more layers in the right?
There're some files for details bellow.
Thanks!
I get a strange voltage drop image (0.2V - 0.0V). There're abrupt changes in the right electrode, but none in the left. What confuses me is that, there are more layers in the right than in the left. How to solve it? Should I add more layers in the right?
There're some files for details bellow.
Thanks!
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