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Topics - sukhito teh

Pages: [1] 2
1
General Questions and Answers / Define a custom dictionary for NRLTightBindingParameters
« on: March 20, 2026, 16:18 »
Dear developers and users,
May I know how do I define NRLTightBindingParameters instead of parsing from the file?

Thank you for your attention.

2
General Questions and Answers / Crystal Field Shift in Slater Koster
« on: February 9, 2026, 09:03 »
Dear developers and users,
is it possible to add different on-site energy to electrons with different magnetic quantum number (e.g. in 10.1103/PhysRevB.102.081103 )?
EDIT:
I know the tutorial provide an example of SK-basis for MoS2 (https://docs.quantumatk.com/tutorials/transmission_gr_mos2/transmission_gr_mos2.html). But for personal reason I cant access the GUI platform, can I know how to obtain the basis from script?
Thank you

3
General Questions and Answers / Module "calculatePlasmaFrequency"
« 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.

4
General Questions and Answers / Effective bandstructure that goes beyond quantuamatk limitation
« on: March 19, 2025, 18:28 »
Dear developers and users,
I am trying to plot the effective bandstructure of a MoS2 Moire Superlattice. Unfortunately the number of atoms in a "unit cell" of Moire Superlattice is not always equal to that of primitive cell, thus I am unable to use the built in EffectiveBandstructure analysis. I humbly ask if any of you can answer the following questions:
1. Is there any workaround to plot the effective bandstructure using quantumatk?
2. Is this limitation inherent from the atomic basis? Is it possible for me to extract internal variable of quantumatk and write my own code (for example using method in this paper https://iopscience.iop.org/article/10.1088/0953-8984/25/34/345501)to plot the effective bandstructure. I suppose I need the overlap matrix and Hamiltonian (which can be assessed through function calculateHamiltonianAndOverlap() )to plot the effective bandstructure. I also hope developers can shed some insights if there's some inherent difficulty in implementing such method, so that I can assess the feasibility of writing the codes. 
Thank you for your attention.
 
Update: the issue was resolved when I set the processes_per_kpoint to 2 increase the threads per process. So I think the error happens due to insufficient memory, contrary to my initial assumption.     

5
General Questions and Answers / Parallelization of ProjectedDensityOfStates
« on: July 25, 2024, 06:42 »
Dear users and staffs,
May I know how parallelization works in ProjectedDensityOfStates ? Lets say I have 4 kpoints, does that mean I should use not more than 4 processes in calculation? And how can I know what is the reduced number of kpoints?
Thank you for your attention.

best regars,
sukhito

6
General Questions and Answers / Constraints_data parameter in function "writePOSCAR"
« on: April 10, 2024, 10:43 »
Dear developers and users,
I am using QATK Version: T-2022.03 . May I know how can I pass information to parameter 'constrained_data' within the 'writePOSCAR' function? Thanks for your attention.

best regards
Sukhito Teh

7
General Questions and Answers / Papers related to DFT-PPS method
« on: December 18, 2023, 13:56 »
Dear developers and users,

Do you know any paper that explain how DFT-PPS method works or use the method to correct electronic bandgap? I tried but unable to find any related paper.  Or is there a general guide on how to optimize the parameters?

Thank you for your time.

Best regards,
Sukhito

8
General Questions and Answers / Inquiry Regarding Local Dielectric Constant Calculation
« on: December 12, 2023, 04:46 »
Dear developers and users,
I am reaching out to seek assistance in reproducing the results presented in a paper titled "Theory of atomic-scale dielectric permittivity at insulator interfaces" https://journals.aps.org/prb/abstract/10.1103/PhysRevB.71.144104.

I am particularly interested in the calculation of the local dielectric constant. For ionic part, the class 'BornEffectiveCharge' can return values for individual atoms, render the calculation of local dielectric constant feasible. However I can't specify which orbitals to be included in OpticalSpectrum class for calculation of electronic dielectric constant, so I wonder if I can use the derivative functions from Class 'BlochState' to calculate the momentum of individual orbital and thus the local dielectric constant. Could you please provide guidance on whether this approach is viable? Additionally, if there exists a more efficient method for performing the calculations, I would greatly appreciate your insights.

Thank you for your time.

Best regards,
Sukhito Teh

9
Future Releases / Dielectric Constant with Local Field Effect
« on: December 8, 2023, 05:31 »
Dear developers,
From what I understand, the dielectric constant obtained from OpticalSpectrum currently does not account for local field effects, rendering it unsuitable for calculating the dielectric properties of 2D materials. I have observed that QATK now offers GW calculations, and I am curious whether the dielectric tensor involved in GW calculation takes local field effects into consideration. If so, is it possible to save these values for further use?

Thank you for your attention to this matter.

Best Regards,
Sukhito Teh

10
General Questions and Answers / Asking for general guide to speed up geometry optimization
« on: October 19, 2023, 07:19 »
Dear developers and users,
I am working on optimization of slab system 100 atoms ~ 500 atoms. The SCF convergence is working fine, but the geometry optimization took long time to converge. The total energy of the system did go down slowly with optimization steps, but the force remain in the order of ~ 1eV/A after 100 optimization steps. Is there a general guide to improve the convergence speed of geometry optimization.  Thank you for your attention

Best regards,
Sukhito Teh

11
General Questions and Answers / SurfaceConfiguration not converged properly
« on: September 30, 2023, 08:11 »
Dear developers and users,
I am trying to calculate work function of TiN using green function method, however the calculation failed to converge nicely at 111 surface, i.e. energy is converged but dQ at central region is still large (~0.15).  The work function obtained seems reasonable, but for other surface calculation, I often obtained dQ that is smaller than 0.01, so I am not sure if I should concern with such value of dQ.

I had also tried different approaches including increases contour points, higher mesh, reducing number of history steps, increase electrode length, central length , but the dQ remained large.

Thank you for your attention

12
General Questions and Answers / Change fermi level in OpticalSpectrum
« on: September 12, 2023, 08:51 »
Dear developers and users,
May I know if there is a way to change the fermi level in calculation of optical conductivity? From what I understand, anomalous hall conductivity (AHC) can be calculated from optical conductivity at E=0. But with the default fermi energy, I can only calculate AHC at the fermi level. Thanks you for your time.

best regards,
Sukhito

13
General Questions and Answers / Unable to open bandgap of FeO (GGA+U & HSE06)
« on: June 3, 2023, 11:36 »
Dear Staffs and Users,
I noticed that both GGA+U and HSE06 failed to open the bandgap of FeO. FYI, calculations with VASP can have similar issue, but those can usually be solved by turning off the K-Points symmetry. However,  even if I am setting use_symmetries  = False in AlgorithmParameters, the calculation still assume time reversal symmetry, so I am not sure if similar approach would solve the problem. May I know if there is any suggestion to solve this problem?
Thank you for your time.

best regards,
Sukhito

14
General Questions and Answers / Local exchange fraction & g in DDHCustomExchangeCorrelation
« on: April 24, 2023, 02:48 »
Dear users and developers,
Is there a way to extract local g or local exchange fraction when implementing local dielectric dependent hybrid in DDHCustomExchangeCorrelation? It would be useful for analysis or fitting ddh paramters.

I also tried to calculate the alpha based on the average g using the attached script, however the value always  differ ( usually about 10%) from the value given by ...exchangeCorrelation().exactExchangeFraction(). Other than that, I also wonder if there's a faster way to obtain derivative of electron density other than using the iteration method as stated in the attached script.
Thank you and have a nice day.

15
General Questions and Answers / Error in Molecular Dynamic Simulation: Particle leaving simulation territory!
« on: March 27, 2023, 18:14 »
Dear ATK staffs and users,
I am trying to implement self-defined CLAY force field in molecular dynamic simulation (ATK2022), but keep getting the error "Particle leaving simulation territory!". If I replace the Si and O force field with Pedone_2006Fe2, then the simulation can run smoothly without problem. A similar problem had been posted earlier (https://forum.quantumatk.com/index.php?topic=6641.msg27814#msg27814), does the errors occur because bond potential is not suitable for molecular dynamic simulation?

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