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17 votes
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What are some approaches to modeling charged point defects in materials?

This is an important question that isn't answered yet, and I've been doing some work with charged defects recently so I'll attempt an answer--though I readily admit I am not really an expert (i.e. I ...
Kevin J. May's user avatar
  • 3,181
14 votes
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How to start with structural defects in monolayer?

First of all, I assume that you are taking VASP to perform your calculation. Secondly, I assume that your structural defect is taking a Hf atom from your structure. (You can deal with substitutional ...
Jack's user avatar
  • 15.2k
8 votes
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Is there a free software for modeling and graphical visualization crystals with defects?

For point defects like a Schottky pair, you can get the defect formation energies from DFT calculations at 0 K or from AIMD calculations at finite temperatures. For these, you can use codes like VASP ...
Mohamed's user avatar
  • 705
8 votes
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Which formalism is better suited to model a crystal with defects: Hartree–Fock, Kohn–Sham, or something else?

Let me first clarify a few things. Whether a calculation is Kohn-Sham or Hartree-Fock has nothing to do with whether the calculation is periodic or not. In fact, both Kohn-Sham and Hartree-Fock can ...
wzkchem5's user avatar
  • 9,710
6 votes

Which formalism is better suited to model a crystal with defects: Hartree–Fock, Kohn–Sham, or something else?

I would like to add a few aspects to the answer of wzkchem5. Considering local or semilocal xc functionals for the KS equations, one difference between HF and KS is that HF is computationally more ...
Gregor Michalicek's user avatar
6 votes
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Relax vs VC-Relax for interstitial incorporation energy

You should use a large enough supercell such that the effect of vc-relax and relax are negligible. This means that the strain due to the impurity is local. The following paper provides a comprehensive ...
liuyun's user avatar
  • 401
6 votes

What are good resources to study crystallographic defects in different dimensional systems and their topological dimensionality?

Arkadiy Simonov and Andrew Goodwin have a nice review out on the arXiv regarding designing disorder into materials, that can elicit unique topological states [1], and there is are some older reviews ...
Phil Maffettone's user avatar
5 votes
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Decide the position of oxygen vacancy via the configuration with the lowest energy?

Introduction Skip at your own risk TiO$_2$ has an equilibrium concentration $c_{eq}$ of all symmetry-unique oxygen vacancies, which is given by $c_{eq} = \frac{N_{O_i}}{N_O} = \exp \left( -\frac{\...
Robert Wexler's user avatar
5 votes

What is the procedure for calculating the formation energy of a doped material?

Defect Formation Energy (DFE) of a point defect The case you described is an example of a point defect (vacancy, substitution/impurity, interstitial) in bulk material. Such point defects can be ...
Abdul Muhaymin -Free Palestine's user avatar
4 votes
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Why my Relax calculation is not stopping?

I agree that the calculation will likely converge eventually and there is likely nothing fundamentally wrong with the calculation itself. However, this is a defect calculation, and it is worthwhile to ...
Andrey Poletayev's user avatar
3 votes

Why my Relax calculation is not stopping?

It will stop, hopefully. Since you set a tighter convergence criteria for the forc_conv_thr than the default value, it is just taking more time. If you check the ...
Abdul Muhaymin -Free Palestine's user avatar
3 votes
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Charged defects in siesta

Yes, it is possible to calculate defect formation energy for a substitutionally doped system in a charged state using the SIESTA code. To calculate the defect formation energy, you need to consider ...
Jaafar Mehrez's user avatar
3 votes

Calculation of charge defect formation energy

First, the energy correction term, $E_{corr}$. It arises due to presence of periodic boundary conditions (defects are spuriously repeated) and of background charge compensation (hidden from the user). ...
Leon A's user avatar
  • 111
2 votes

How to interpret defect formation energy diagram?

Why defect formation energy is plotted against $E_F:$ Let's go step-by-step. First, let us look at the Defect Formation Energy (DFE) formula: $$ E_f^D(q,E_F) = E^D(q)-E^{\mathrm{host}}-\sum n_i\mu_i + ...
Abdul Muhaymin -Free Palestine's user avatar
2 votes
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How to determine defect charge state degeneracies?

I used the method in this paper and this paper and it worked well: To summarize: The defect degeneracy level (the total # of charge carriers created by the defect) should be determined. Combinatorics ...
rmza7's user avatar
  • 329

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