Recent Posts

1

General Questions and Answers / Re: Change the temperature of the device.

« Last post by zwh on Today at 03:14 »

Dear Expert,

I have a question regarding the temperature-related parameters. As shown in Figure 1, does the term "broadening" here refer to Fermi broadening? Additionally, in Figure 2, does "Electrode temperature" indicate the temperature of the device?

If I aim to simulate the IV curves of a device at different temperatures (considering the impact of temperature on transfer characteristics), should I primarily adjust the "Electrode temperature" parameter?

Thank you for your guidance!

2

Scripts, Tutorials and Applications / Customising a new potential

« Last post by Priyadarshini on Yesterday at 16:50 »

Hi everyone,

I'm following the Combining Potentials tutorial (https://docs.quantumatk.com/tutorials/combining_potentials/combining_potentials.html) in QuantumATK W-2024.09, and I'm encountering an error when trying to run a script that combines force fields.

Here’s the error traceback:

TypeError: The parameter charge = 1.098 must have a unit that can be converted to e.

It seems to be triggered by this line (or similar logic) in the script:

setParticleType(particleTypeSymbol='O', mass=1.9994*AtomicMassUnit, charge=-1.098)
I double-checked the usage of AtomicMassUnit and e, and I’m unsure why it says the parameter can’t be converted to e when units appear correct.

Has anyone else seen this issue or can suggest what might be causing the unit conversion error here?

Thanks a lot in advance!

3

General Questions and Answers / "optimizedeviceconfiguration" module does not have an output file.

« Last post by zwh on April 16, 2025, 07:54 »

Hi everyone, I hope you can help me resolve this issue.
When using the "optimizedeviceconfiguration" module for device optimization, the optimized device model is missing from the HDF5 file. I'm not sure what the problem is—could it be that I missed something during the setup?
Please help me take a look. Thank you for your help!

4

General Questions and Answers / I have a question regarding the piezoelectric tensor manual.

« Last post by wntjr1024 on April 10, 2025, 11:37 »

Here are two ways to obtain the piezoelectric tensor using AlN as an example. The first method is to obtain e33 (piezoelectric tensor) by simply inserting the piezoelectric tensor block in the orthorhombic structure and running it. However, in the second method, the piezoelectric tensor block calculates the clamped-ion approximation. I wonder what criteria are used to obtain e33 (piezoelectric tensor) and e33(0) (the clamped ion approximation piezo tensor). I would appreciate it if you could clearly and specifically explain the difference between the two.
I would appreciate your reply.

5

General Questions and Answers / Twister

« Last post by gayani2025 on April 10, 2025, 06:56 »

Dear All,

Dear All,

This is my first time using QuantumATK, and I am currently working through some tutorials to get familiar with the software.


I noticed that there is an option called "Twister" (Exploring Graphene tutorial). However, I am unable to locate this feature in the version I’m using (W-2024.09-SP1).

Could you kindly guide me on where to find this option or let me know if it has been relocated or renamed in this version?

Thank you very much for your assistance.

Best regards,
GN

6

General Questions and Answers / Why is the polarization value of AlN different from the experimental value?

« Last post by wntjr1024 on April 9, 2025, 08:58 »

I optimized AlN with a hybrid GGA using an LCAO calculator with a maximum force of 0.03 eV, and then obtained the polarization and piezo electric tensor, but they are very different from the experimental values. I would like to know the cause of this.

my AlN polarization data

my AlN piezoelectric tensor data


and reference data

7

General Questions and Answers / Langevin MD simulation friction variation

« Last post by Lim changmin on April 9, 2025, 07:53 »

Hello,

I'm currently performing melt-quench molecular dynamics simulations to generate amorphous structures using the Langevin thermostat. In the Langevin method, there's a friction parameter (with a default value of 0.01).

When I use the default value, the system's temperature rapidly rises to unphysically high values like 1e12 K or 1e11 K. However, when I increase the friction coefficient to 0.05 or 0.1, the temperature starts to fluctuate reasonably well around the reservoir temperature.

Still, for some structures, the temperature control is not stable enough. So I'm considering increasing the friction coefficient further to 0.15 or even 0.2.

Here are my questions:

Would increasing the friction coefficient to this extent affect the resulting amorphous structure?

From a theoretical standpoint, how much can I increase the friction coefficient before it starts to significantly affect the dynamics and structural outcomes? Is there a practical or theoretical upper limit?

Kindly waiting for the response.

8

General Questions and Answers / Re: Module "calculatePlasmaFrequency"

« Last post by filipr on April 8, 2025, 09:06 »

The function returns the plasma frequency, i.e. the square root of the expression in the documentation.

9

General Questions and Answers / Probably the convergence problem during execution_Reg.

« Last post by techenthusiast on April 7, 2025, 12:21 »

Is it possible in a conventional case?  For lower VDS up to =0.15V (along with VDS=0.15,0.3,0.4,0.5,0.8,1V) is giving somewhat acceptable results whereas VDS=0.05V (for the same device) doesn't provide suitable results. Maybe because of the convergence problem during execution. Kindly share yours's viewpoints.

10

General Questions and Answers / Module "calculatePlasmaFrequency"

« Last post by sukhito teh on April 6, 2025, 15:33 »

Dear developers and users,
Does the function calculatePlasmaFrequency returns plasma frequency or square of plasma frequency? The formula in documentation https://docs.quantumatk.com/manual/Types/OpticalSpectrum/OpticalSpectrum.html#opticalspectrum-c uses ω², but the return value has unit of energy. Thank you for your attention.