I have been trying to reproduce the results of the following paper: " Negative differential resistance in nanoscale transport in the Coulomb blockade regime - Prakash Parida et al 2009 J. Phys.: Condens. Matter 21 095301 ". A code is being developed for this, and all the parameters are taken to be same as in the paper.
With all the considerations according to the paper, the final current is coming out to be incorrect; there is some leakage current at zero source-drain bias (i.e. at Vsd=0). With further analysis of the issue, it appears that transitions are occuring between 4e states and 3e states, which is incorrect.
I have not found any issues with implementation of the theory in the code. Any suggestions in this regard would be extremely helpful.
To address the issue you're facing with leakage current and unintended transitions between charge states in your simulation based on the paper "Negative differential resistance in nanoscale transport in the Coulomb blockade regime,"
here are a few suggestions:
1. Check Your Model Parameters: Ensure that all the parameters used in your simulation match exactly with those mentioned in the paper. Parameters in such simulations, including tunneling rates, capacitances, and temperature, can significantly affect the results.
2. Review Charge State Transitions: The unintended transitions between 4e and 3e states suggest a possible issue with how the charge states are being modeled or calculated. This might be due to an error in the energy configuration or the tunneling rate equations used. Re-examine these parts of your code to ensure that they correctly implement the theoretical model.
3. Boundary Conditions: Verify the boundary conditions used in your model, particularly at Vsd=0. Sometimes, numerical simulations can introduce errors at boundaries if not handled correctly.
4. Numerical Stability and Discretization: Check if the numerical methods and discretization steps used in your simulation are stable and accurate. Inaccuracies in numerical methods can lead to erroneous results, especially in quantum transport simulations where tunneling and interference effects are sensitive to numerical details.
5. Debugging the Code:
- mUnit Testing: Break down your simulation into smaller units or modules and test each module individually. This can help isolate the part of the code that might be causing the problem.
- Logging and Monitoring: Implement logging at critical points in your code to monitor the state transitions and current calculations step-by-step.
6. Software and Tools: Consider whether the software or the programming environment itself might have any known issues or bugs that could affect calculations at specific conditions like zero bias.
7. Alternative Approaches: If you continue to encounter problems, consider testing the model with alternative computational approaches or tools to see if the issue persists across different methods.
If these steps do not resolve the problem, it might be useful to look at publications or resources that cite this paper to see if any subsequent studies have addressed similar issues or have modified the model in any
Good luck !
H
Respected Prof. Shore,
Thank you for your kind suggestions. I am currently re-evaluating the code-implementation along these lines.
Regards,
Koushik R. Das
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