13 votes

How to start with the optical properties of 2D materials with the VASP code?

Due to the enhanced coulomb interaction and the quantum confinement effect in the two-dimensional limit, the optical properties should be investigated with the GW+BSE method. The practical calculation ...
Jack's user avatar
  • 15.1k
12 votes

How to start with the optical properties of 2D materials with the VASP code?

The VASP manual is always the first resource to check, you can find it here. As a beginner, following "Getting Started" should help you greatly, from how to install the code, some details of ...
ProfM's user avatar
  • 11k
9 votes
Accepted

Optical proprieties with Quantum espresso

There will be 4 output files in total for an epsilon.x run. These are: ...
Abdul Muhaymin's user avatar
9 votes
Accepted

Why can't we change the spin angular momentum of electrons with an external optical field?

This has already been asked in several forms in Physics Stack Exchange. Within the semi-classical 'electric dipole' approximation, only the electric field of light interacts with the electron. The ...
Xivi76's user avatar
  • 2,392
8 votes
Accepted

Calculating hyperpolarizability in NWChem

Major Issue The major issue here is that NWChem doesn't support second-order response in the DFT code: "Response calculations are currently supported only for order 1 (linear response), single ...
Jeff Hammond's user avatar
8 votes
Accepted

Why does my zincblende structure not look cubic?

I think the premise of your question is mistaken. The structure you have shown in your question is the primitive cell of Zincblende. It is not cubic. The conventional structure has a face-centered ...
Abdul Muhaymin's user avatar
7 votes

Optical spectra beyond electric dipole approximation

Observation of a pure electric quadrupole mechanism for a solid-state electronic transition A pure electric quadrupole electronic transition was observed for single crystals of $\ce{Cs2UO3Cl4}$. In ...
Antonio de Oliveira-Filho's user avatar
6 votes
Accepted

Would it be appropriate to use a Van der Waals-DFT approximation in Quantum ESPRESSO to study the properties of my material (p-type semiconductor)?

No, van der Waals functionals would not be appropriate for this type of system - at least, not normally. Most semiconductors of interest are strongly bonded 3D materials, with covalent bonds and ...
Phil Hasnip's user avatar
  • 7,312
6 votes

How can we make a mechanically unstable cubic system, stable

Depending on your calculation and how much time you want to invest in getting the best property you can, I suggest two different approaches to make this system stable: Fully relax the geometry of the ...
Brandon Bocklund's user avatar
6 votes

Why can't we change the spin angular momentum of electrons with an external optical field?

well, you certainly can change the spin of an electron through acting on its orbital motion with the electric field. It is called "spin-orbit coupling" (SOC) and a lot of magneto-optical and ...
sleepy's user avatar
  • 291
5 votes

Can the color of gold metal be reproduced by modeling only the conduction electron band structure, or do atomic absorption lines contribute?

A band can either be expressed as a linear combination of plane waves, or as a linear combination of atomic orbitals. By asserting that the color of gold can be explained by relativistic shifts of ...
wzkchem5's user avatar
  • 9,630
5 votes

Why is there a large discrepancy between calculated frequency dependent dielectric function and experimental measurement?

Wait, those are two very different resonances. The one at 150-200 nm is obviously of electronic origin, whereas the one at about 12 microns is related to phonon modes. There is quite a lot of ...
sleepy's user avatar
  • 291
5 votes
Accepted

Why is there a large discrepancy between calculated frequency dependent dielectric function and experimental measurement?

It's not obvious to me that you are doing anything wrong in your calculation. Your result for the crossover energy seems consistent with the literature, e.g. Theodorou et al. (1999) and Petalas et al. ...
Anyon's user avatar
  • 4,741
5 votes

Optical anisotropy from first-principles

As something of a frame challenge, I would argue that DFT should be suitable for these kinds of calculations. At least for molecules, DFT is probably the most common way to compute circular ...
Tyberius's user avatar
  • 15.5k
5 votes

Why can't we change the spin angular momentum of electrons with an external optical field?

I think the claim assumes linear polarization of the light which has zero angular momentum. For circularly polarized light, the spin of the electron should be flipped. (e.g. Appl. Phys. Lett. 114, ...
Xiaoming Wang's user avatar
5 votes
Accepted

Are there any other options beyond increasing the k-sampling and the number of unoccupied bands, to achieve better results?

After a few months working with Aluminum-based structures, I'm confident to respond to my own question. And the answer is NO. Keeping in mind that I'm using the IPA (independent particle approximation)...
Anibal Bezerra's user avatar
5 votes
Accepted

A good software for DFT optimization and nonlinear optical properties

So I've used Gaussian as it is one of the few codes that can calculate hyperpolarizability for a lot of DFT functionals. My input is very staightforward, hope it will help someone. ...
Roman's user avatar
  • 2,373
5 votes
Accepted

Optical properties without LOPTICS tag

When you open the LHFCALC tag, the DFT hybrid functional type dielectric function is calculated. All the output files you obtain are calculated by ...
Jack's user avatar
  • 15.1k
5 votes

Optical spectra beyond electric dipole approximation

For magnetic dipole transitions, it seems well-known examples are Eu3+ doped phosphors, for example, Eu3+:Y2O3 and Eu3+ chelates. The $^5D_0 \rightarrow ^7F_1$ transition is magnetic dipole allowed, ...
Xiaoming Wang's user avatar
4 votes

Studying computing on HSE06 in VASP

As per my comment, If OP is referring to dielectric tensor for "optics", examples can be found here from the VASP Wiki. For the density-of-states (DOS), the VASP Wiki has a tutorial here. ...
CW Tan's user avatar
  • 1,276
3 votes
Accepted

Why linear response is absent in a non-centrosymmetric system with time reversal symmetry?

You left off a key phrase from the paper. Noncentrosymmetric systems with time reversal symmetry don't have nonreciprocal linear response. Linear response on its own doesn't have this property. For ...
Tyberius's user avatar
  • 15.5k
3 votes

How to implement scissor-correction in VASP to study optical properties?

For VASP, the model BSE method implements scissor operator correction to calculate the optical properties in the BSE framework. In particular, you can follow this tutorial. However, this method is ...
Jack's user avatar
  • 15.1k
3 votes

Evaluating absorption coefficient using VASPKIT for nanostructures (specifically quantum dots)

Based on the comments, it seems that this is not possible in VASPKIT.
3 votes

Can the color of gold metal be reproduced by modeling only the conduction electron band structure, or do atomic absorption lines contribute?

Lets start with some data from Optical Transmission in Thin Metal Films where they deposited a range of metals on glass and measured their transmission. Sticking with their data on the noble metals, ...
Jon Custer's user avatar
3 votes

Optical Band gap determination from absorption coeffecient using DFT

You can calculate the optical gap with TDDFT or GW/BSE. GW/BSE is more common in solids. These are more expensive calculations than DFT calculations, but they are commonly done in metal-halide ...
AGS's user avatar
  • 1,100
3 votes
Accepted

optical properties in IR region

Let's start by putting aside the DFT for a moment and consider the experimental system. That has a bandgap of ~ 4 eV (i.e. somewhere in the UV -- the precise number is irrelevant to the discussion!). ...
Robert Lawrence's user avatar
3 votes
Accepted

Why my values of dielectric function don't match litterature (For Yambo with Quantum ESPRESSO)?

The plot in the reference paper is in the Arbitrary unit. So, the absolute value doesn't matter. The value can be 1 in the paper and 1000 in your calculation - it is not a problem. I think the only ...
Abdul Muhaymin's user avatar
2 votes

How to plot the dielectric function calculated with Yambo?

After I repeated the calculation so many times I figured out that the problem arise if you use k-points {automatic}. When k-points {gamma} is used the problem is fixed and just 1 ...
Camilla's user avatar
  • 2,129
2 votes

Optical Band gap determination from absorption coeffecient using DFT

This is not the actual answer that you asked, but you can get some insight from here. I believe the optical gap is equal to the direct electronic gap at T=0K at a certain k point. Still some more ...
1 vote
Accepted

Query about optical absorption spectra

It seems like an answer that was satisfactory to the OP was written in a comment by Andrey Poletayev: "E || a should be xx, E || c should be zz. The equivalent of yy should be E || b." ...

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