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General Questions and Answers / Analyzing Interface Dipoles
« Last post by evansjc on June 13, 2025, 23:08 »
Hello,

I am trying to gather as much information as I can on the interface dipole formed between two materials (dielectric/dielectric or dielectric/semiconductor). Are there any analyses or calculations that would be recommended to gain as much information as possible about the magnitude and direction of the dipole? I am trying to understand how this dipole changes when the interfacing materials are changed.

Thank you!
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We always plot things from the electron perspective, so yes if you view it from a hole perspective, you need to invert. Also the current direction changes for holes.
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We had a very detailed explanation of this on the website, but it's been lost. Also, it is not entirely correct anymore, but while we create a modern version, you can see the old one at https://web.archive.org/web/20140605201318/http://quantumwise.com/publications/tutorials/mini-tutorials/99-how-to-set-up-the-electrodes-properly-in-a-two-probe-system.
Note that the electrode length in the old version of the code should now be understood as the equivalent electrode length; that is, in the newer QuantumATK implementations, the electrode itself can always be kept minimal, whereas now the equivalent electrode length (which is part of the central cell) should obey the rules laid out in the link above for the "electrode length".
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You need to reverse the order of the steps - you are computing the DynamicalMatrix (DM) for the primitive celll (2 atoms), but passing the STD supercell as "configuration" to PhononBandstructure. You should compute the DM for the STD config.
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Hello,

I was looking through past webinars and I saw this figure (attached) in the 2021 webinar titled "Atomistic Simulations of Defects & Dopants with QuantumATK" at the 11:00 minute mark. What is this figure referencing? Are these internal QuantumATK results or are they results from a paper? Are the methods used to obtain these results detailed anywhere? I would appreciate any information on this.

Thank you!

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Hi Anders,

Great! Thank you!
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Thank you for your reply. I found the link you provided very helpful.
However, I still have a few questions I’d like to ask.
To calculate the phonon band, a BulkConfiguration and a Dynamic Matrix are required.
(The Dynamic Matrix can be obtained using the empirical potential in the ForceField (FF) calculator.)

The Special Thermal Displacement (STD) can also be computed using the empirical potential to generate a temperature-dependent Dynamic Matrix and a new configuration.

By combining STD, phonon band, and tensoff, I believe I can meet my simulation needs.
However, I encountered an error in the results (e.g., NLValueError, etc.).

the error message:
NL.ComputerScienceUtilities.Exceptions.NLValueError: The underlying configuration must be equal for the input DynamicalMatrix and the object being calculated.
NL.ComputerScienceUtilities.Exceptions.NLValueError: The underlying configuration must be equal for the input DynamicalMatrix and the object being calculated.
rix and the object being calculated.

(More detailed information is included in the attached image.)

Do you have any suggestions on how to resolve this error?
Thank you very much.
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how long electrode length should someone use? In generally .... Thanks
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Thanks for the message !!!
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