Messages

16

General Questions and Answers / Re: energy convergence issue in perovskite LaMnO3

« on: August 21, 2025, 18:44 »

HI
Do u mean electron convergence or atomic force convergence?

For former, decrease the damping factor to 0.01 &/or history steps to 12.
For latter, try rattling of atoms around mean position.

17

General Questions and Answers / Re: Transport properties for Optimized Structures

« on: August 21, 2025, 18:40 »

Hi
This happens because QATK does not recognise the atoms in your electrode (left and right end) as repetitive after geometry optimization.
A way around is to use tag on few layers of atoms on left/right end and keep them fixed during optimization of central region but be careful this may introduce internal strain.
A better is way is to fix left side atoms of your material and keep right side atoms as rigid. Also, put a vacuum on the right side so that the rigid atoms can move into vacuum for proper relaxation. Then post relaxation remove vacuum using fit cell and you can easily create device.

18

General Questions and Answers / Re: how to restart Defect MTP Training after interruption

« on: August 21, 2025, 18:36 »

HI
Unlesss u had checkpoint, I think u need to restart.

19

General Questions and Answers / Re: NPT MD with Z-axis relaxation only (MD constraints)

« on: August 21, 2025, 18:35 »

hi
Check under constraints in MD and optimization block and use tags for atoms you want to constraint.

20

General Questions and Answers / Re: Issues with AdaptiveDampingFactor in X-2025.06 version

« on: August 21, 2025, 18:32 »

Hi, Why would you choose it as adaptive instead of default 0.1 or below?
Incase you are facing convergence issues try it as 0.01

21

General Questions and Answers / DFT Phonon Transmission

« on: August 21, 2025, 18:30 »

Dear Admin,

I want to calculate phonon transmission across an interface of two 2D materials. The dimension are device are 7.83 A in periodic direction and a vacuum in out-of-plane direction and a total number of atoms as 153. In the dynamical matrix, it shows default repetitions as 3x1x1 however, which increases total atoms to 459.
This increases computational time very much beyond few weeks. Therefore, I used repetitions as 1x1x1.

I want to know is it the right approach and how would it affect my results if I don't use repetitions?
Also, would the approach be at-least useful for qualitative results?


Thanks

22

General Questions and Answers / Re: Problem in attaching the electrodes after device central optimization

« on: July 11, 2025, 13:46 »

Hi did you keep any layer fixed during optimistic?

23

General Questions and Answers / Re: GPU QATK

« on: June 28, 2025, 05:28 »

Thanks, Anders Blom,

It's resolved now. The error mentioned that it was not recognizing "qatk_gpu" when running a GPU simulation. Later, I found that the older version of Smart Keys didn't have any description of "qatk_gpu"
So, had to update the smart keys, and it worked nicely.

I might have some questions regarding the speedup. I am still testing it.

For someone facing the same issues, kindly redownload your SmartKeys from the Solvnet and replace them with the old ones.

24

General Questions and Answers / Re: GPU QATK

« on: June 25, 2025, 02:48 »

Update: I tried re-installing new SCL license but the issue still remains. It gives the same error.

25

General Questions and Answers / Re: Request for Feedback on Spin Transport System Setup

« on: June 23, 2025, 19:14 »

Hi,
You don't need to use a vacuum when optimizing the bulk Ni or gold unit cell. Just optimize the bulk unit cells and then cleave 111 out of it.

Also, I see you have chosen a very less K-point sampling. The default for Ni is 12x12x1, and you have used 6x6x1.
Also, use a density mesh cutoff of around 110 Hartree.

The actual way to figure out these numbers is to calculate the total energy of the unit cell at various density mesh cutoff and K point sampling, and see at what values the total energy converges. Generally, the larger the supercell, the less K point sampling is required, and the smaller the cell, the larger the K point sampling.
Also, whether you want to optimize with/without cell optimization depends on which one gives you the right lattice parameters. This can you verify with literature or experiments.

26

General Questions and Answers / Re: Request for Feedback on Spin Transport System Setup

« on: June 23, 2025, 07:29 »

Hi,

The tutorial you referred to uses a device configuration where you don't need to add a vacuum in the z direction; it takes care of it internally. However, the configuration you have shown in the pic is a bulk configuration. To optimize it as is given in the tutorial, you need to first convert your bulk configuration into a device, which you can do in the builder. In the builder, select your configuration from the stack, and then on the right, choose Device from the bulk.

27

General Questions and Answers / Re: Request for Feedback on Spin Transport System Setup

« on: June 20, 2025, 15:58 »

Hi,

Just my few cents:
If you are optimizing this configuration as bulk, you will need to add a vacuum in the z direction (to avoid spurious interaction between Ni and Au) and keep either electrodes (say Ni) outer layer fixed to emulate bulk behavior. At the same time, you need to keep the gold outer layer rigid (or fixed in xy direction) so that it can move in the z direction to avoid any internal stresses during optimization. This way, you can optimize the structure.
Also, make sure the gold and nickel are optimized from the bulk unit cell before forming the interface. Also, choose a low-strain interface from Interface Builder (though it depends on computational complexity).

Also, I wanna know if initial spin has any effect on the final optimized configuration or just helps in quick optimization?

28

General Questions and Answers / GPU QATK

« on: June 19, 2025, 03:31 »

Dear Admin,

I recently installed the X-2025.06 version of QuantumATK, which supports GPU acceleration for DFT calculations.
In the bin folder, I found the following files:
atkpython
atkpython_gpu
atkpython_system-mpi
quantumatk

In the mpi/bin, I found the following files:
cpuinfo
hydra_bstrap_proxy
hydra_nameserver
hydra_pmi_proxy
impi_info
mpiexec
mpiexec.hydra

Kindly let me know if this is how to run DFT simulations on GPU:

atkpython_gpu input.py > output.log

or

mpiexec.hydra -n 2 atkpython_gpu input.py > output.log (2 here for using 2 GPUs on a given node)
My GPU node shows 6 GPU machines when using nvidia-smi command.

If I am doing it incorrectly, kindly help me do it properly for single-GPU and multiple-GPU machines on a given node.

Also, do we require any licenses to use GPU acceleration because I tried atkpython_gpu input.py > output.log and it shows:
License Error: Unable to obtain a required license for the
requested license feature. It could mean there are no valid
licenses left, a problem with the connection to the license
server, or the license file does not contain the requested feature.
See below for more details.
No such feature exists.
Feature:       qatk_gpu
License path:  [email protected]:
FlexNet Licensing error:-5,234

29

General Questions and Answers / Re: Error while opening QATK in windows 11

« on: June 4, 2025, 18:24 »

Sadly no. I deleted them all

30

General Questions and Answers / Re: Error while opening QATK in windows 11

« on: June 2, 2025, 15:18 »

Dear Anders Blom,

The older version was from 2023.
The files that were causing trouble were in the path: C:\Users\Lenovo\.quantumatk
It was the .quantumatk folder that was causing the trouble.

Yes, there was a popup just after I double clicked the QuantumATK icon.