Messages

1

General Questions and Answers / Issue to apply uniaxial stress on built heterostructure properly

« on: August 16, 2025, 14:05 »

Hi all,

May I know how to apply stress (uniaxial) on heterostructure built and observe the changes in energy band structure. However, there appear to have a really direct method which is simply to "stretch cell" by controlling A, B and C sliders. Wondering if it is correct with this method? Or actually must gone through "optimize geometry" and follow step by step according to the tutorial (as per link given: https://docs.quantumatk.com/tutorials/uniaxial_biaxial_stress/uniaxial_biaxial_stress.html#introduction)?

Please advice and your support really matters to me.
Looking forward to hear from you soon.

Kind regards,

2

General Questions and Answers / I need help on bader charge analysis

« on: February 18, 2025, 03:04 »

Dear Sir,

I am trying to understand charge transfer using bader analysis. I tried to simulate the graphene with H2O attached to it. However I got a few errors. Please can anyone help me how to solve this.

3

General Questions and Answers / Re: How to extract the equivalent molecules concentration ?

« on: February 18, 2025, 02:47 »

Dear Sir,

My apology for repost. I am still figuring out on how to extract the equivalent concentration. My material is graphene with H2O (water) molecule attached to it. Is there any way to extract the equivalent H2O concentration. I am attaching herewith the picture for H2O attached on graphene.
I appreciate any feedback from the expert.
Thank you.

4

General Questions and Answers / How to extract the equivalent molecules concentration ?

« on: January 21, 2025, 20:07 »

Dear Sir,

I am studying gas sensing effect on graphene. I watch video tutorial as this link ..https://www.youtube.com/watch?v=BeDbeDztQeY&t=98s ...I am seeking help from expert to guide on how to extract the equivalent molecules concentration as demonstrated in this video.
Thank you

5

General Questions and Answers / Nothing appear on the I-V curve

« on: January 2, 2025, 12:25 »

Dear experts,

I have H2O molecules on graphene on hexagonal boron nitride. I have place left and right electrode as shown in the picture (see picture 1) to simulate the I-V characteristic. The simulation took almost 2 days and nothing appear on the I-V curve once the simulation completed (see picture 2). I would like to seek help from expert for me to understand this problem. Is there any problem related to the settings or placement of molecule ? The I-V characteristic appear if without molecules.

6

General Questions and Answers / Re: Why the adsorption is on substrate ?

« on: December 25, 2024, 06:23 »

Thank you sir for the response. I really appreciate it

7

General Questions and Answers / Why the adsorption is on substrate ?

« on: December 24, 2024, 05:24 »

Dear Sir, I am referring to this Youtube tutorial link (https://www.youtube.com/watch?v=1k6aYnv0l-8&list=PLkOUx2yxHrqwoIJ_t6fAInqAKn12BpaGL&index=8) from QuantumATK on simulating adsorption of molecules on this material. The picture of my structure model is as attached (see picture adsorption 1). I attempt to use H2O molecules on my heterostructure. My question is why the H2O molecules is on the substrate and not the top layer. I also try to change the surface level and recalculate it back. Now the H2O molecules is below the top layer and still not on the most top layer (see picture adsorption 2). My aim is to have the H2O molecule on the top most layer which in this case is graphene. I appreciate any feedback from the expert. Thank you.

8

General Questions and Answers / How to build graphene/h-bn

« on: November 23, 2024, 19:44 »

Hi everyone, i hope to find help.
Im trying to study monolayer graphene/h-bn heterostructure and find the lattice mismatch between them. I understand that interface is used to create heterostructure, as i follow this tutorial https://docs.quantumatk.com/tutorials/ag_au_interface/ag_au_interface.html. But im having hard time in constructing it (as in picture below). I need guidance and tips.
Thankyou

9

General Questions and Answers / Introduce strain

« on: January 15, 2023, 14:08 »

I want to introduce strain to (1-D nanoribbon). I have read past discussion on strain in the forum and i get a little confused. I need help from expertise. Is this how strain is introduced ? (here i attach picture of before and after strain). Can expertise correct me if i do it wrong way.

From bulk tools:
-> lattice parameters (lattice type in "unit cell" and i keep "fractional coordinates")
-> repeat (i repeat along C-axes)
->stretch cell (i select all atom, and i did strain in A-axes by "moved" it ). Here i did strain 1%.

Do i need to include together optimize geometry under bulk calculation ?
Really appreciate anyone reply to this. Thank you.

10

General Questions and Answers / Why the curve does not showing like typical id vds characteristic of mosfet ?

« on: October 31, 2022, 05:54 »

I currently studying BC2N nanoribbon with back gate. I need help, i was wondering why the curve does not showing like typical id vds characteristic of mosfet.

Here are the settings I used:
-Lcao calculator
-left & right electrode in lcao calculator : 0V
-Multi-grid solver type, where (A & B) i put Neumann, and C i put Dirichlet.

Below i attached the side and front view of BC2N with back gate structure, and the id vds obtained. I appreciate any help and suggestions.

11

General Questions and Answers / Error occured

« on: October 24, 2022, 13:34 »

Im trying to run my simulation. After i send script to job manager, this messages of error popup. Can anyone guide me what should i do ?
I really appreciate it.

12

General Questions and Answers / Re: Can we know the concentration used of the studied gas ?

« on: October 20, 2022, 20:56 »

Thank you Sir for your reply. But Sir, the concentration of gases used in experiment might be different from simulation. Or can we know the concentration for each molecules ?

13

General Questions and Answers / Can we know the concentration used of the studied gas ?

« on: October 16, 2022, 18:35 »

Hi, i need help. Can we know the concentration used of the studied gas ? Is there any features on the specification for the concentration of the studied gas?

14

General Questions and Answers / Metallic in spatial region voltage

« on: September 16, 2022, 08:04 »

Hi, i was trying to design a device using bc2n with back gate. I have followed the tutorial and found about the setting for spatial region, please see picture below. Could you please explain to me about metallic voltage. Is there any ideal value to set for metallic voltage ? Is it okay to put 0V. I was trying to produce current vs gate-source voltage using Iv characteristic.

15

General Questions and Answers / Re: Bending or twister

« on: September 7, 2022, 09:47 »

Thankyou Dr Blom   i finally able to do it