Questions tagged [solid-state-physics]
Questions about solid state physics.
67
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In solids physics, how are Van Der Waals forces modelled?
I'd like to know how to treat VdW interactions among layers. Specifically I'm using Quantum Espresso and I'd like to know how VdW forces are implemented in the Kohn-Sham equation. Does it insert a $V \...
5
votes
1
answer
120
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Negative band gap in DFT calculations
I am performing DFT simulation (with Quantum Espresso) for a large number of crystalline materials to estimate their band gap energies. I am getting negative band gap values for many of them (...
3
votes
0
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38
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Hilbert transform on the Bethe Lattice
In order to compute the local Green's function on the Bethe lattice, it is necessary to perform a Hilbert transform
$$G_{loc}(\omega) = \int \frac{DOS(\varepsilon)}{\omega-\varepsilon} \text{d}\...
- 136
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The "Tetrahedron method does not include variations of the Fermi occupations" Problem
I am doing computation of tetragonal CsPbBr3 perovskites.
When I set ISMEAR = -5 I found such a problem:
This problem is absent at ISMEAR = 0. What is the cause of the problem and how do I solve it?
- 331
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How is magnetization of a solid obtained from electron density in a DFT framework?
What's the theory behind these kind of calculation? What are keywords and concepts I have to search for?
- 103
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429
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Difficulty in interpreting electronic band structures in solid state physics
My background is in ab initio calculations of atoms and molecules, and I consider myself to have a good understanding of the underlying quantum theory of electronic structure and electronic spectra ...
- 400
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39
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Antibonding, non-bonding or bonding hybridization
In case of CsSnI3 and CsGeI3 perovskites, the strong antibonding hybridization of Sn-s/Ge-s state with I-p state lies near to VBM of these materials. In this informative paper (P.No.13853, 14th line), ...
- 395
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432
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Simulated STM Image with Quantum-ESPRESSO's pp.x
Context: I am an undergraduate "self-taught" noob when it comes to QE. (I've just been using online resources and textbooks thus far.) There are no QE or DFT experts at my university (I have ...
- 113
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139
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Can specifications of a second-order phase transition of a solid be obtained with the Hartree-Fock (or DFT) calculation?
At some temperature a crystal lattice of a solid can be rearranged or to say it more precise - got new positions of its cores. This phenomenon is well-known to be called a second-order phase ...
- 857
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51
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Kohn anomaly and avoided crossing (or anticrossing/level repulsion)
Kohn Anomaly and Avoided Crossing (Anticrossing/Level Repulsion) are terms that are found to be used when discussing phonon dispersion. The former (see last paragraph, page 198) is related to electron-...
- 395
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What makes the inhomogeneous electron gas more interesting than its homogeneous counterpart?
This question is asked in the context of the famous paper on DFT by Hohenberg and Kohn. What makes the inhomogeneous electron gas more interesting than its homogeneous counterpart?
- 395
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353
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Why do we not get DOS by summing over all the PDOS?
If we sum over all the PDOS (Projected/Partial Density of States), will we have the total DOS or simply the DOS? This was not the case in my DOS and PDOS results for a simple Al atom. I am wondering ...
- 2,031
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196
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Optimzation for Large supercell
I am trying to optimize a copper supercell for the study of chalcones adsorption using Quantum ESPRESSO, however, the size of my supercell is large (>200 atoms) and QE can not handle it.
What is an ...
- 505
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35
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Excited state frequency for periodic systems
Is there any way to calculate the excited state frequencies of a period system using DFT?
- 21
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I'm considering to take an introduction course with textbook "Materials Science and Engineering: An Introduction", as a beginner QE user. Is it okay?
People, I am a beginner in material modeling (I am studing solid state in Quantum ESPRESSO) and I am having a lot of difficulty with basic terms like "k-points", "Miller Indices", &...
- 505
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1
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397
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Screened Coulomb interaction and its direct Fourier transform
I have a question concerning the screened Coulomb interaction in periodic systems.
Many first-principle DFT codes provide the possibility to compute linear response functions, such as the irreducible ...
- 297
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Can we create a phonon with a specific wavenumber that persists in the system for a long time? [closed]
The phonon number is not a conserved quantity, they add up as dictated by the dispersion relation until the Planck distribution is reached. However, I would need the k=PI/a phonons not to disappear ...
- 21
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Which properties would you study to evaluate spatial confinement of a molecule
I'm modelling molecules confined within porous materials and I was wondering which molecular properties would you consider to access the confinement.
Í'm thinking about looking into long-range ...
- 353
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164
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How to find which atoms/bonds contribute to the particular section of band structure?
In this paper, in the first sentence of page no.6723, the authors attribute a particular section of band structure (in momentum space) to the bonds/ atoms in real space. I would like to know methods ...
- 395
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How to do parity analysis of band extrema?
To check whether electronic transitions are allowed between valence band maximum (VBM) and conduction band minimum (CBM) as per Laporte's rule, the parity of VBM/CBM is needed to be known. This paper ...
- 395
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What happens to the position coordinates of the nearest neighbors in supercell studies?
Can anyone tell what happens to the position coordinates of the nearest neighbors when we choose to study supercell of the same material. That remains intact or any changes will be there?
For example ...
- 123
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The polarization lattice of a non-polar one dimensional chain [closed]
I have been trying to understand the concept of dielectric polarization in material science mostly by following Nicola Spaldin's lecture notes
I am confused by the claim that the polarization of a non-...
user5405
4
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1
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How to map high symmetry points from primitive cell to conventional cell?
We usually plot electronic bands with the help of high symmetry points of the irreducible zone of primitive cell of particular material. But if we want to plot bands with conventional cell, we have to ...
- 123
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How to download METADISE code?
I have a (possibly trivial) question regarding the METADISE code. I can find the documentation related to this code, but I cannot find the download page or tarball anywhere.
Can someone kindly share ...
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How to get a Wannier function for a tight-binding model numerically? [closed]
I have a question about construction of a Wannier function for a tight-binding model. Let's say we consider the tight-binding model of a 1D chain with two atoms (site A and B in a unit cell). In k-...
- 161
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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 ...
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51
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Cutoff energy in Quantum ESPRESSO calculation [duplicate]
What is cutoff energy in solid state calculations? I would just like a detailed explanation and the applicable formulas!
- 3,751
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1
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196
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How to find the Cauchy stress tensor in solids using ab-initio methods?
I want to find the Cauchy stress tensor in certain materials with ab initio methods. I already have the analytical form of my own definition of "energy" and "forces" (not from DFT),...
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244
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What Wyckoff position to put in Input file of Unit Cell of TiCoSb?
$\ce{TiCoSb}$ has Wyckoff position as
...
- 1,095
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2
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467
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Mobility and chemical potential
I have been studying the Boltztrap2 software to calculate the thermoelectric properties of materials. However when following the tutorial given, the Seebeck coefficient is plotted against ...
- 133
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Why the band structure of a slab is not smooth?
I am trying to calculate the band structure of a TiO2-Rutile slab, but the result I got is not very smooth, and the result shows it is an indirect gap material, but the bulk phase of TiO2-Rutile is a ...
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31
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Do the VBM and CBM have to be on the high symmetry point? [duplicate]
I am trying to generate the band structure of a slab, a lot of tutorials tell me that I need to generate the high symmetry K point path, but I am wondering that if the VBM and CBM have to be on the ...
- 1,938
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How to numerically calculate quantum state distance using quantum metric?
In Ran Cheng's review of the quantum geometric tensor, eq. (11) gives the tensor as:
$$
Q_{\mu\nu}=\sum_{n\neq 0}\frac{\langle\phi_0|\partial_\mu H|\phi_n\rangle\langle\phi_n|\partial_\nu H|\phi_0\...
- 2,131
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Which software is suitable for visualizing the electron wavefunctions in a crystal?
I'd like to use the tight-binding model with a linear combination of atomic orbitals.
It should show the full energy bands, as well as the spatial probability distribution for each eigenfunction of ...
6
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217
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How to define ferrimagnetism in Quantum ESPRESSO [closed]
I would like to pick this problem from my previous post See link.
I am clear about how to define antiferromagnetism in QE.
Here I am with another issue.
I am ...
- 1,663
9
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453
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Why is the planewave codes ecosystem healthier on free/opensource software adoption, when compared to codes supporting atom-centered orbitals?
Regarding the branch of matter modeling that deals with electronic structure methods, I think we can divide it in two camps: Those who work mostly with planewave-based software, geared towards ...
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Constructing the symmetry operator from k.p Hamiltonian [closed]
I have a question regarding to how to construct an operator from k.p Hamiltonian. Maybe there are some problems in my understanding, I hope you can point me out and correct my description if I made ...
- 2,763
11
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1
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286
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Transition dipole matrix element
When doing DFT calculations of periodic solids, from either $\mathbf{k \cdot p}$ perturbation theory or simply using the trick $\mathbf{r} \rightarrow i\partial_{\mathbf{k}}$, one can obtain
$$
\...
- 2,048
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Constructing an anisotropic crystal in WulffPack [closed]
I am trying to create an $\ce{LiFePO4}$ crystal in WulffPack. I have the surface energies of seven different surfaces from the paper [1]. When I input the same to WulffPack, it creates a structure ...
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What are properties of interest for energy storage materials?
In the field of simulation for energy storage materials, there is always a gap between theoretical calculations and demand for experimentalists. What could be directly calculated from ab initio ...
- 3,751
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4
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Good books about computational chemistry of solid state materials for newbie
At the University, I chose the organic chemistry path and to better understand my experimental works I started studying computational chemistry on my own. There are a lot of books in this field, but I ...
- 1,459
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949
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Increasing k-point grid to take DOS calculation
I was trying to compute some electronic properties for Pd using SIESTA and VASP for some computer practicals in my university, specially focused on band structure and density of states (DOS) using LDA ...
- 967
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Example of a standard/archetypal/simple 4-band gapped condensed matter model with analytic results? [closed]
I am looking to study Berry phase-like phenomena in a gapped 4-band material model. In particular, I want to numerically and analytically calculate the Abelian Berry curvature integral of each band ...
- 2,131
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Example of a standard/archetypal/simple 4-band un-gapped condensed matter model with analytic results?
I am looking to study Berry phase-like phenomena in an un-gapped material model. However, I am having trouble finding a widely-used 4-band model with analytic expressions for wavefunctions and ...
- 2,131
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Can I have a bond formed for only one spin?
I'm making a topological analysis of a nanotube interacting with some metals.
The steps for the calculations were:
Optimizing the geometry (I am using SIESTA code).
Obtain the electronic density for ...
- 21.9k
11
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1
answer
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Methods to determine the vacuum level in 2D compounds in the presence of dipoles
When 2D compounds have a dipole, the potential distribution becomes linear (the left panel of the figure). After considering the dipole correction, the potential has two plateau regions in the vacuum (...
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What does a density of states (DOS) plot show?
I have plotted the density of states using GGA-PBE exchange correlation functional for magnesium silcide but I really do not know what the equations involved are in this process, and how they relate ...
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Why does numerical computation of Berry curvature give me a correct Berry phase when it is supposed to diverge? [closed]
I implemented the standard numerical algorithm for calculating the Berry curvature in MATLAB. For a given 2D system, I can visualize the Berry curvature over parameter space. If I sum the Berry ...
- 2,131
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What's the difference between dynamic and static strain aging? [closed]
I do understand how static strain aging occurs and why the yield point comes back if ample time is allotted after a loading and unloading cycles primarily due to diffusion of substitutional and ...
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What will break the time-reversal symmetry?
Specifically, I am interested in the time-reversal symmetry $(\mathcal{T})$ in quantum mechanics. The $\mathcal{T}$ is considered as an anti-unitary operator, namely:
$$\mathcal{T}\psi(\vec{r},t)=\psi^...
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