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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 flow is the following if you are considering using VASP Perform a ground state DFT or hybrid calculation. Based on previous converged charge density and ...


11

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 the background theory, and how to run simple calculations.


9

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 effect of magnetic field is usually very weak except for a few cases like highly concentrated pulses etc. Magnetic field can flip spins, in a process called 'spin-...


8

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 frequency, electric field and mixed electric-magnetic field perturbations." [1] The NWChem coupled-cluster response property capability supports ...


6

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 structure. Some comments below your question suggest that you tried to fully relax your structure, but the structure is probably not fully relaxed if it is ...


6

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 opto-magnetic (inverse) effects completely rely on it. You might want to look at papers discussing all-optical magnetization switching with circularly ...


5

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 atomic orbitals, one have implicitly expanded the conduction band wavefunctions into a linear combination of atomic orbitals. Then it follows easily that if an ...


5

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 experimental data on SiC properties in the infrared, so if you're looking for the experimental data in the uv range, you might want to specify the range in the search. ...


5

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. (1998) (the former being a computational work, and the latter a synchrotron experiment). What you should note, however, is that you are using a very different ...


5

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 birefringence and circular dichroism and it seems to give reasonable agreement with experiment. When more accurate calculations are needed, CCSD calculations are used, ...


5

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, 041104 (2019)) Indeed, it has a probability issue as explained by @Xivi76.


5

When you open the LHFCALC tag, the DFT hybrid functional type dielectric function is calculated. All the output files you obtain are calculated by VASPKIT using this dielectric function. https://vaspkit.com/tutorials.html#optic-properties Could someone please explain to me, if we are getting the files for optical properties, then how reliable are these ...


4

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. %NProcShared=24 %mem=192Gb %Chk=optfreq.chk #P B3LYP/Def2TZVP Opt Freq Optfreq 0 1 *Here goes initial geometry* --Link1-- %NProcShared=24 %mem=192Gb %OldChk=optfreq.chk %Chk=...


3

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, they see pretty much what one would expect - some changes in shape as the film thickness goes from 0.5 to 4nm of gold, coupled with the clear emergence of the ...


3

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 example Electric Polarizability is the linear response of the dipole to a change in the electric field and this in general is nonzero for noncentrosymmetric and ...


2

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 able to deal with bulk materials. For two dimensional materials, you can use YAMBO and BerkeleyGW.


1

I took a look at the files posted on the Research gate platform. I'm not used to the VASP, but the results you reported are a bit strange. I've got the same kind of outputs using the EELS package from the Quantum ESPRESSO library, which uses the Quantum Liouville equation for the charge-density susceptibility. The reason may be the approximation VASP uses ...


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