Questions tagged [solid-state-physics]
Questions about solid state physics.
82
questions
20
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1
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What class of materials are closest to realizing the tunable coupling Hamiltonian?
From a physics point of view, there is an effective (approximation to second-order coupling Jaynes-Cummings) Hamiltonian of the form [1]
\begin{equation}
H=\sum_j\omega_j(t)\sigma_j^z+\sum_{\langle i,...
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18
votes
4
answers
847
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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 ...
- 1,509
17
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12
answers
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Is it better for me to study chemistry or physics?
I might decide to pursue material science.
Aptitude and background
I am from the UK, and for A-levels, I am studying Maths, Further Maths, Physics and Chemistry, and I am predicted decent grades in ...
- 179
17
votes
5
answers
1k
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What are some open-source all-electron DFT alternatives to Wien2K?
Since the beginning of the century, Wien2K has proven to be a very powerful player in computational condensed matter and materials physics.
Wien2K is an all-electron periodic DFT code based on the ...
- 4,889
16
votes
0
answers
263
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Why does the Wolff algorithm slow down in a 4-body Ising model? [closed]
In the paper that introduced "Self-learning MC" (an ML-inspired MC technique, as I understand) the authors consider a many-body Ising model as an example to show the efficiency of their ...
- 681
14
votes
1
answer
1k
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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 ...
- 987
14
votes
1
answer
6k
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Labeling of high symmetry points in Brillouin zone
A Brillouin zone is defined as a Wigner~Secitz primitive cell in the reciprocal lattice [1,2].
The construction of the first Brillouin zone for two different 2D lattices are shown below:
The ...
- 24k
13
votes
1
answer
702
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Ising models with many-body interactions
I find it surprisingly difficult to find researches/papers on systematic "many-body interaction" extensions of the Ising model. Can somebody tell me a good review/article etc on this matter ...
- 681
13
votes
1
answer
3k
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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 ...
- 1,615
12
votes
2
answers
127
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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 ...
- 3,973
12
votes
1
answer
4k
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How to understand the crystal field splitting of d-orbitals in a trigonal prismatic geometry?
This question is coming from this paper, which investigated the spontaneous spin and valley polarizations of monolayer LaBr2.
The geometric information of monolayer LaBr2 is displayed as following (Br:...
- 15.3k
12
votes
1
answer
339
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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
$$
\...
- 2,098
11
votes
2
answers
1k
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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 ...
- 2,087
11
votes
1
answer
215
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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 (...
- 675
10
votes
2
answers
457
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Morse potential for phonons in solids instead of the harmonic potential approximation?
As the title says, the Morse potential (https://en.wikipedia.org/wiki/Morse_potential) is an exactly solvable model in quantum mechanics, just like the quantum harmonic oscillator. Extensions of it ...
- 188
10
votes
1
answer
685
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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 ...
- 624
10
votes
1
answer
6k
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What is the physical meaning of occupations='smearing' in Quantum ESPRESSO?
I want to understand, what is the intuition behind using the occupations='smearing' or 'tetrahedra' in Quantum ESPRESSO input file? I mean how we can interpret what is going to happen inside of ...
- 2,621
10
votes
1
answer
110
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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 ...
- 24k
10
votes
0
answers
95
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What are the methods of modeling Jahn-Teller effects in a solid-state material? [closed]
The Jahn-Teller effect arises from the symmetry breaking (distortion) of the local environment for the crystal field of 3d transitional metal ions.The distortion result in energy saving of electronic ...
- 3,973
9
votes
2
answers
3k
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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^...
- 15.3k
9
votes
1
answer
463
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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 ...
- 4,128
9
votes
1
answer
250
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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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9
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0
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163
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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 ...
- 889
9
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0
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177
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Is the non-trivial band topology in a system, caused by spin-orbit-coupling or band inversion? [closed]
How can we know that the non-trivial band topology in a system is driven by spin-orbit coupling (SOC) or by band inversion?
Based on my understanding, SOC causes the band inversion and makes the ...
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8
votes
2
answers
701
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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
8
votes
1
answer
969
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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 ...
- 133
8
votes
1
answer
375
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 ...
- 2,663
8
votes
1
answer
300
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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 ...
8
votes
1
answer
895
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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 ...
8
votes
1
answer
335
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How to calculate the orthogonal representation of a HCP cell?
I'm trying to write a program to calculate the neighbor lists of crystal systems. I found a few codes that are able to calculate it for orthogonal systems. How can I do it for non-orthogonal cells ?
...
- 273
8
votes
1
answer
1k
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How to perform virtual crystal approximation calculations in VASP?
Can someone share appropriate tags and methods to perform virtual crystal approximation calculations in VASP?
- 691
8
votes
1
answer
592
views
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
8
votes
1
answer
407
views
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\...
- 2,381
8
votes
2
answers
111
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Combined effects of strain and doping on the electronic structure of semiconductors
I've read papers in DFT studies on band gap tuning in semiconductors and the usually studied methods are either through doping or application of external strain. But it is always just one or the other....
- 1,161
8
votes
0
answers
112
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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 ...
- 81
8
votes
0
answers
122
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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 ...
- 2,381
8
votes
0
answers
142
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Can we calculate bond enthalpies for each bond in a supercell of a disordered AB crystal using DFT? [closed]
Apart from using Bader charge analysis or energy of formation estimation, I wonder if there is a way to compute the bond energy of constituent bonds in a crystal using density functional theory.
Let's ...
- 5,195
7
votes
2
answers
204
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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?
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7
votes
1
answer
129
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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 \...
7
votes
0
answers
40
views
How to determine if hybridization takes place between orbitals in an ab initio calculation using Quantum ESPRESSO?
I'm using Quantum ESPRESSO to determine the electronic properties of systems. Now I want to confirm if hybridization takes place between orbitals. I have generated density of states and projected ...
- 453
6
votes
1
answer
150
views
Charge density wave and band inversion
Is there any connection between charge density wave and band inversion? Or is there any system in which band inversion follows the same mechanism as the CDW? I am just trying to find a connection ...
- 691
6
votes
1
answer
353
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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 (...
6
votes
1
answer
373
views
What Wyckoff position to put in Input file of Unit Cell of TiCoSb?
$\ce{TiCoSb}$ has Wyckoff position as
...
- 1,532
6
votes
1
answer
74
views
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 ...
- 2,381
6
votes
1
answer
205
views
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?
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votes
0
answers
675
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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
6
votes
0
answers
270
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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 ...
- 1,673
6
votes
0
answers
143
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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 ...
- 2,923
5
votes
1
answer
172
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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 ...
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5
votes
1
answer
248
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elastic constants transformation/basis change P21/a -> P21/n
I just calculated the stiffness tensor for a given material (a monoclinic molecular crystal)
using molecular simulation. When trying to compare my results to published experimental results
I found ...
