Messages

1

General Questions and Answers / Re: silicon raman peak shifting /phonon band at higher Temperature

« on: June 7, 2025, 14:46 »

Thank you for your reply. I found the link you provided very helpful.
However, I still have a few questions I’d like to ask.
To calculate the phonon band, a BulkConfiguration and a Dynamic Matrix are required.
(The Dynamic Matrix can be obtained using the empirical potential in the ForceField (FF) calculator.)

The Special Thermal Displacement (STD) can also be computed using the empirical potential to generate a temperature-dependent Dynamic Matrix and a new configuration.

By combining STD, phonon band, and tensoff, I believe I can meet my simulation needs.
However, I encountered an error in the results (e.g., NLValueError, etc.).

the error message：
NL.ComputerScienceUtilities.Exceptions.NLValueError: The underlying configuration must be equal for the input DynamicalMatrix and the object being calculated.
NL.ComputerScienceUtilities.Exceptions.NLValueError: The underlying configuration must be equal for the input DynamicalMatrix and the object being calculated.
rix and the object being calculated.

(More detailed information is included in the attached image.)

Do you have any suggestions on how to resolve this error?
Thank you very much.

2

General Questions and Answers / silicon raman peak shifting /phonon band at higher Temperature

« on: June 3, 2025, 09:37 »

To simulate the thermal effects on the Raman peak shift (or phonon band) of silicon, the typical approach involves DFT + MD simulations (e.g., VASP + DynaPhoPy https://www.sciencedirect.com/science/article/pii/S0010465517302631#b5, or Quantum ESPRESSO + Phono3py). Since QuantumATK is based on Quantum ESPRESSO, it is also possible to perform MD simulations using FF Calculator with empirical potentials (e.g., Tersoff).

I would like to achieve a similar simulation—specifically, the temperature-induced shift of the Raman peak. I am currently using QuantumATK version 2023.12-SP1.

Could you please provide some guidance, example scripts, or options within QuantumATK that would help me carry out such a simulation? Thanks.

3

General Questions and Answers / How to fit the optical constants of silicon?

« on: September 25, 2024, 07:13 »

I tried using the silicon alpha data to simulate the optical constants of silicon from the paper by D. E. Aspnes and A. A. Studna: Dielectric functions and optical parameters of Si, Ge, GaP, GaAs, GaSb, InP, InAs, and InSb from 1.5 to 6.0 eV (Phys. Rev. B 27, 985-1009, 1983), but I found that the results did not match well.
Are there any methods to improve this? Thank you.