Topics

1

General Questions and Answers / Forcefield potential for dopant diffusion simulation in Si

« on: February 19, 2023, 06:56 »

Hi all,

I try to simulate typical dopant diffusion (B, P, As) in Si, SiGe, and Si/SiGe heterostructure.
I consider to use MD simulation, but I could not find any good potentials.
Then, is the only approach that I can use creating ML-FF?
Please give me any advices on this.

Thanks.
jiwon

2

General Questions and Answers / PackMole file for amorhpous HfO2 structure

« on: February 1, 2023, 13:19 »

Hi all,

I was studying mtp generation for HfO2.

https://docs.quantumatk.com/tutorials/mtp_hfo2/mtp_hfo2.html

In the step 2, we need amorhpous structure for active learning.
And the amorphous HfO2 is first generated using PackMole followed by FF based geometric optimization.

Can I get the script for the initial HfO2 structure generation using PackMole?
Of course, if I could get the FF optimization file as well, that will be even better.

Thanks.
jiwon

3

General Questions and Answers / meaning of energy cutoff value for LCAO DFT calculation

« on: November 12, 2020, 09:35 »

Hi,

I have a basic question about energy cutoff.
Basically, energy cutoff defines the energy limit for plane wave basis set.
Then, what is the meaning of energy cut off if I use LCAO basis set for DFT?
Can anyone explain this?

Thanks.
jiwon

4

General Questions and Answers / Ge Bandstructure pps-PBE

« on: October 7, 2020, 08:58 »

Hi,

I have a question on Ge band structure calculation shown in this link.
https://docs.quantumatk.com/tutorials/dft_half_pps/dft_half_pps.html

I tried to follow the calculations using files (bulks.py, pbe.py, pps.py) which I can download from the above link.
I could run pbe.py, but I got into licence error issue when I tried to run pps.py which is for adjusting the Ge band gap.
To run pps-DFT, do we need a special license for ATK?

Can you please give me any advices on this issue?

Thanks.
jiwon

5

General Questions and Answers / Unit of Transmission

« on: January 28, 2020, 13:38 »

Hi

I have question about the unit of transmission which we get from the transmission calculation.
Let's say that we have periodic structure in transverse direction like an example below.
https://docs.quantumatk.com/tutorials/transmission_gr_mos2/transmission_gr_mos2.html
And I want to calculate current/width [A/um].
Then, the transmission that I get from the calculation in the above example should be divided by the width of real space unit cell. (of course, I need to multiply it with e^2/h)
Am I doing right?
I just want to confirm the dimension of the transmission that I get from quantum ATK.

Thanks.
jiwon

6

General Questions and Answers / SCF converge issue in Optimization

« on: September 25, 2019, 23:59 »

Hi

I am trying to do geometry optimization of a certain 3 layers of 2D materials.
I have issue in the scf convergence.
To resolve the scf convergence issue, I tried to increase k point and energy cut off. But both didn't work for my case.
I attached my input file of 9x9x1 k point and output log file.
In the first several scf loop converge, but it fails.
I have tested increased k point, but the result is same.

Please give me any advices to solve scf issue in optimization.

Thanks.
jiwon

7

General Questions and Answers / work function of bulk material

« on: August 28, 2019, 07:02 »

Hi,

I want to know how to calculate the work function of bulk material.
ATK tutorial about calculating work function is for slab structure having vacuum. And it seems that vacuum is required to set a energy reference.
However, in bulk system, since we don't have vacuum, it is hard to set up any reference by setting up boundary condition.
So, can  we calculate work function of bulk material with ATK?

Thanks.
jiwon

8

General Questions and Answers / unit of transmission spectrum and DOS

« on: July 9, 2019, 08:15 »

Hi,

I have a question about the unit of transmission in the example below.

https://docs.quantumwise.com/tutorials/transmission_gr_mos2/transmission_gr_mos2.html

In this example, we calculate transmission of rectangular unit cell of graphene and MoS2.
In the graphene example, it shows how transmission spectrum changes with the number of k-points in the transverse modes.
And my question is what is the unit of Transmission.
Since it is a periodic structure in the transverse direction, transmission unit should be #/m or #/um, but the picture showing transmission it is not clear.

Is the default unit in the transmission spectrum just # or #/m?
If it is just #, then I guess we need to divide it with the length of rectangular unit cell in the transverse direction (y-direction).


I also have similar question for DOS calculation.
If I calculate DOS for 2-D material, then the unit for the calculated DOS in ATK is just #/eV or is it normalized with area?

Thanks.
jiwon

9

General Questions and Answers / monolayer MoS2 electron affinity calculation

« on: June 19, 2019, 04:27 »

Hi

I tried to calculate the electron affinity for monolayer MoS2.
I used informations which I could find in the link below.
https://forum.quantumatk.com/index.php?topic=5270.msg23352#msg23352
https://forum.quantumatk.com/index.php?topic=5114.msg22147#msg22147
https://docs.quantumwise.com/tutorials/work_function_ag_100/work_function_ag_100.html#work-function-ag-100

I want to confirm that what I did is right.
I introduce one sulfer ghost atom and set the boundary conditions as mentioned in the tutorial.
Then, I ran chemical potential calculation.

I attatch my script file here. Please take a look and let me know if this approach is right.

Thanks.
jiwon

10

General Questions and Answers / 2D rectangular Contour plot

« on: October 19, 2018, 11:16 »

Dear,

The attachment py file is about Hexagonal contour plot (conduction band).
I want to know how to make "rectangular" contour plot.


Thanks
jchang

11

General Questions and Answers / Adjusting energy grid in DOS calculation

« on: March 7, 2018, 05:09 »

Hi,

I want to increase the resolution for DOS calculation.
But, it seems that it is not supported.
Is there any way to manually put the dE, Emax and Emin for DOS?

Thanks.
jiwon

12

General Questions and Answers / energy contour plot for band structure

« on: January 19, 2018, 06:15 »

Hi,

I wonder if there is a way to generate energy contour plot for the BZ as in the attached file.

Thanks.
jiwon

13

General Questions and Answers / Running multiple VNL

« on: January 15, 2018, 22:23 »

Hi,

I have a trouble to run more than one VNL.
Whenever I try to run more than one VNL (for example, running one VNL in my server and the other in my lab top), I got license configuration error.
So, running only one VNL is allowed.
I have three parallel running license. And I though # of VNL execution simultaneously does not depend on the # on licenses. But even if it is true, I can run only one VNL.
Can you explain me why I have this issue?

Thanks.
jiwon

14

General Questions and Answers / Parallelization of PDOS calculation

« on: January 8, 2018, 00:44 »

Hi,

I have tested PDOS calculation using different number of cores.

It seems that assigning more cores does not help to reduce the running time.
I have tested 2, 4 and 40 cores.

In my calculation, I have converged potential calculation for a device.
Device is periodic in the device width direction (direction perpendicular to the transport direction).
So, I use several transverse modes in the calculation.
And # of transverse mode is 29.

I thought PDOS calculation might be parallelized in transverse modes, but it seems not because I don't see much speed up with more cores.
Can anyone tell me how parallelization of PDOS calculation is done?
If I understand this, I think I could assign cores more wisely.

Thanks.
jiwon

15

General Questions and Answers / Image file generation from builder

« on: December 20, 2017, 03:34 »

Hi,

I am trying to generate image file from builder.
Is there any options to control the quality of image? It seems there is no control over it.
And can we control the background color in builder? I know that we can change the background color when we save it in image, but I want to know if it is possible changing the background color in builder itself.

Thanks.
jiwon