Recent Posts

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51
General Questions and Answers / Re: Issue on running MTP training simulation
« Last post by AsifShah on November 26, 2025, 04:36 »
Hi,

Just a small suggestion. Instead of going with MTP, I would suggest fine-tuning a MACE mode which is more accurate than MTP. The fine tuning is also very simple. You can go throught his tutorial.

 "https://docs.quantumatk.com/tutorials/mace-training-c-am-TiSi/mace-training-c-am-TiSi.html"
52
General Questions and Answers / Re: Questions Regarding GPU Acceleration
« Last post by AsifShah on November 26, 2025, 04:34 »
On the same note,

I am using RTX 6000 Ada but there is no speedup. The CPU runs faster than GPU.
Any idea, why? Will these issues be resolved in next version of QATK?
53
General Questions and Answers / Re: Questions Regarding GPU Acceleration
« Last post by dmicje12 on November 25, 2025, 08:17 »
Thanks you for your reply!
54
General Questions and Answers / Re: Questions Regarding GPU Acceleration
« Last post by filipr on November 24, 2025, 14:01 »
I am not aware of any benchmarks on Volta series GPUs. We mainly have access to A-series hardware. Depending on the calculations you do the bottleneck of the program will often be in CUDAx libraries like cuBLAS and cuSolver, so you can search for benchmarks of these.
55
General Questions and Answers / Re: Questions Regarding GPU Acceleration
« Last post by dmicje12 on November 21, 2025, 03:01 »
Thank you for your response!
I would like to know how your team evaluated the acceleration performance of the V100. Was the improvement significant?
I understand that the V100 is certainly not as powerful as the A100 or H100, but how does the V100 compare to a server-grade CPU (such as the EPYC 7F72 shown in the manual)?
Thanks!
56
General Questions and Answers / Difference Between electrode_extension_lengths and equivalent_electrode_lengths
« Last post by kaihuang on November 21, 2025, 00:06 »
Hi all,

Could anyone clarify the physical meaning of electrode_extension_lengths in the device configuration, and how it influences the calculation results? The manual only states that it is “the desired equivalent electrode extension length of each electrode,” which is not very informative.

In a related forum discussion (https://forum.quantumatk.com/index.php?topic=10735.0), it was mentioned that the calculation results depend on this parameter. What is the underlying theory for this dependence?

We already have the parameter equivalent_electrode_lengths, which defines how much of the central region should be equivalent to the electrodes which is clear. But how is electrode_extension_lengths fundamentally different?

In older versions of the manual and ATK (e.g., https://docs.quantumatk.com/tutorials/atk_transport_calculations/atk_transport_calculations.html), this parameter did not exist.
57
General Questions and Answers / Re: Questions Regarding GPU Acceleration
« Last post by filipr on November 20, 2025, 18:55 »
QuantumATK relies on the PETSc library for some sparse matrix operations. It appears that PETSC uses one of a few specialized CUDA functions that are not compatible with newer compute capabilities (your RTX 5080 has compute capability 12.0 = SM120 as per this chart). Basically your GPU is too new to be used for the PETSc library shipped with QuantumATK. The compatible compute capabilities has to be chosen when compiling the PETSc source code, so it is baked in. So for now you can't use your RTX gpu for doing calculations that involve PETSc operations.

However, even if it did work it likely wouldn't be faster than running on CPU. RTX 5080 is a GPU primarily designed for graphics processing and it only has 384 FP64 floating point units - 2 per streaming multiprocessor, so reportedly you only get 1/64 of the FLOP throughput. Scientific calculations mostly rely on 64 bit floating point numbers for accuracy in the algorithms. For scientific computations one should use specific GPUs with many FP64 units as is the case for the A, H and B series data center GPUs.

The RTX 5080 sounds like a blast for gaming, though  8)
58
General Questions and Answers / How to obtain I–V curves for MTJ devices (parallel and antiparallel states)
« Last post by tahereh2647 on November 20, 2025, 12:14 »

Hi everyone,
I am working on MTJ (magnetic tunnel junction) devices and I would like to calculate the I–V characteristics for both P and AP magnetic configurations.
I have a few questions:
1. Which calculator and settings should I use to obtain the I–V curves for MTJ devices?
• For example, what type of calculator is appropriate and what are the important settings (k-point sampling, bias range, etc.) for reliable I–V results?
2. Is it a good approach to first calculate the transmission spectra  and then use a Python script to compute the I–V curve from the transmission data?
3. Or is it better to use the built-in “IVCharacteristic” analysis in the Workflows to directly obtain the I–V curve?
• If so, how should I set it up correctly for an MTJ device in the parallel and antiparallel states?

Thank you in advance for your guidance!
59
General Questions and Answers / Questions Regarding GPU Acceleration
« Last post by dmicje12 on November 19, 2025, 16:07 »
Hello everyone, I would like to use my RTX 5080 for GPU acceleration.
However, after running I get the following message:

**Back Engine Exception : PETSc error 76 of type 0 in MatSeqAIJCUSPARSECopyToGPU:2488: This program was not compiled for SM 120
: cudaErrorInvalidDevice: invalid device ordinal
** Location of Exception : petsc_impl.h:90
May I ask if the RTX 5080 is currently not supported? Or is there any other way to enable GPU acceleration with the RTX 5080?

Thank you, everyone!
60
General Questions and Answers / Question about non linear particle swarm optimization parameter
« Last post by Lim changmin on November 19, 2025, 04:34 »
Hello,
I am trying to use the NonLinearParticleSwarmOptimizationParameters (NLPSOP) for testing purposes. In the TiSi MTP tutorial, it is mentioned that NLPSOP can define the MTP more accurately, so I wanted to try it in my training script. I attached the NLPSOP settings I used as Figure 1.

However, when I run the script, I get the following error:

AttributeError: 'NonLinearParticleSwarmOptimizationParameters' object has no attribute 'initialCoefficients'. Did you mean: 'initialCoefficientsFromFile'?

Could you please let me know how to properly use NLPSOP when training an MTP? In particular, I would like to know:
1. How to correctly specify the NLPSOP block in the training script, and
2. How to set and use initialCoefficientsFromFile (e.g., what kind of file is expected and how to generate it).

Thank you in advance for your help.
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