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Questions tagged [quantum-dots]

Questions about or related to quantum dots.

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3 votes
1 answer
93 views

Error in TranSIESTA: "The electrode down-folding region is 0 in the device region"

When I run a tranSIESTA calculation, the SCF converges, and the TBtrans output shows the following error: ...
4 votes
0 answers
251 views

Calculation of Carbon Quantum Dots using Quantum ESPRESSO [closed]

I have build a carbon quantum dots model based on this paper. The model looks like this. I have calculated the density of states of the system, but does not get a desired plot as written on the paper,...
3 votes
0 answers
126 views

Transiesta SCF not converged [duplicate]

I have encountered a convergence problem in my structure device in Transiesta calculation, the calculation doesn't converge. Recently I try to decrease the mixing weight parameter to 0.00001. For some ...
9 votes
2 answers
2k views

Why does Quantum ESPRESSO need 13TB of RAM for a (3x3x3)nm supercell?

I made a 3nm×3nm×3nm supercell mesh of pbs atoms which contains about 2000 atoms and QE gave me a 13256 GB requirement of RAM. What am I doing wrong? Many people have already done this calculation, ...
16 votes
2 answers
2k views

How to understand the spin of exciton?

In very recent years, exciton physics has been intensively explored as the emergence of 2D materials. Exciton is a bound electron-hole pair and is bosonic, namely hosting an integer spin. My first ...
3 votes
0 answers
50 views

How to cut a Nano material from a cif file properly [closed]

I am not asking which software to use to or how to remove atoms from a supercell. But rather how to decide which part should be removed. Like do I give preference to some surfaces or some particular ...
8 votes
2 answers
298 views

Geometrical Optimization not converging for a double perovskite quantum dot, using Gaussian

I am trying to optimize the geometry of a Cs4CuSb2Cl12 Stoichiometric Quantum dot and I have checked the input multiple times, but the opt+freq calculation is not converging. The quantum dot has about ...
8 votes
1 answer
343 views

Can deformation potential theory be applied to 2D and 1D systems?

I was pointed towards the use of the Deformation Potential (DP) theory to calculate the electron relaxation time in a previous question. However, I still have a doubt regarding its applicability to 2D ...
9 votes
1 answer
1k views

Error while doing a band structure calculation in Quantum ESPRESSO

I have been using BURAI GUI of Quantum ESPRESSO to calculate the optical properties of ZnSe quantum dots. But first I wanted to calculate the electronic band structure. After running the calculation ...
7 votes
0 answers
66 views

Is it necessary to terminate the surface ions in a quantum dot? [closed]

I was trying to study quantum dots of ZnO. But I'm pretty new to creating and passivating 0-dimensional particles. Is it always necessary to passivate the free surface of the quantum dot? Regarding ...
8 votes
0 answers
117 views

How to compare the stability of two nano-structures using ab-inito calculations? [closed]

I have recently started working on Double Perovskites Quantum Dots and one of the main issue with them is that they are not much stable. Some papers did talk about how much stable there compounds are ...
6 votes
0 answers
162 views

How to run Quantum ESPRESSO on Google Cloud Services or Amazon Web Services [duplicate]

As I am exploring material simulations one really hard truth that I have realized is that my gaming laptop is not at all going to cut it for my research work. Currently I am trying to find the ...
7 votes
1 answer
3k views

SCF Calculation not converging after two decimal places in Quantum ESPRESSO

I have been trying to do geometrical optimization for ZnSe Quantum Dots using Quantum ESPRESSO. The convergence is very slow, so slow that even after 200 iterations I could not get convergence. I ...
11 votes
1 answer
342 views

Geometrical Optimization not converging, where am I going wrong?

I am trying to obtain the optical properties of ZnSe Quantum Dots, the problem is that my geometrical optimization is not converging. I used VESTA to create the structure(there is a photo in the ...
7 votes
0 answers
85 views

How to passivate the surface of ZnSe Quantum Dot and apply vacuum to it? [closed]

I have been trying to simulate ZnSe zinc blende quantum dots using Quantum Espresso and its GUI BURAI. But being a beginner I am a little confused about a few things: How do I passivate the surface, ...
9 votes
1 answer
452 views

How can I know if 3D aperiodic systems are not interacting with each other using Quantum ESPRESSO?

I wanted to observe the Projected Density of States of InP system passivated with Hydride ions. For that, the following input file was created. ...
15 votes
2 answers
498 views

Quantum Dot properties using VASP

We are working on the excitonic properties of cadmium-based Quantum Dots (QD) and QD heterostructures. We have MedeA-VASP and hence we managed to make QD structure. Are QD calculations different from ...