Questions tagged [condensed-matter]

For all matters related to condensed matter physics.

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3 votes
0 answers
33 views

Energy corrections to be added in my DFT input of Quantum ESPRESSO for studying catalytic activity of MoS2 for hydrogen evolution reaction

While investigating 'catalytic activity of MoS2 (monolayer) in hydrogen evolution reaction', what are the energy corrections that I am supposed to add in the DFT input (using Quantum ESPRESSO) to get ...
3 votes
0 answers
42 views

convergence not achieved after 80 iterations [closed]

I am trying to run a scf calculations to obtain the band structure. However, in the output file, it is show that the convergence is not achieved after 80 iterations. ...
1 vote
0 answers
90 views

Disappearing vacuum layer when relaxing bilayered hBN with VASP

I'm doing geometry optimization of bilayer h-BN, a 72-atom supercell (6x6x1) with vacuum thickness of 20 Å, and I set the parameters in INCAR as below: ...
6 votes
0 answers
55 views

Modelling a porphyrin with a metal with just the p_z and d orbitals

We have a porphyrin-like molecule with a transition metal atom in the center, like the one shown in the figure. Consider first the porphyrin without the metal. In such a case, several orbitals around ...
2 votes
1 answer
61 views

Equilibrating Surface Temperature Through NVT Ensemble Ab Initio Molecular Dynamics

In my AIMD simulations with the NVT ensemble at T= 300K (Nosé–Hoover thermostat)for a Pd (111) surface (2*2, 6 layers) and vacuum sizes of 14 Å and 18 Å, All other INCAR tags are same(only NGZ for 14Å ...
3 votes
0 answers
76 views

How did they calculate the indirect radiative recombination rate in this paper?

In this paper they calculated radiative recombination rates for Germanium using an effective mass model and I am trying to calculate the indirect spontaneous radiative recombination rate related to ...
3 votes
1 answer
189 views

Why does the C6z operator have 6 eigenvectors in this paper?

In this paper, I couldn't understand this line in the 3rd section (i.e. III. SYMMETRY ARGUMENTS): In the absence of SOC, the eigenvalues of $C_{6z}$ rotation operator are $e^{i2\pi n/6}$ where $n = 0$...
2 votes
1 answer
173 views

Choice of SMASS for AIMD simulations in VASP

How can one verify that the values (0, 1, 2, and 3) in the SMASS parameter correspond appropriately to the NVT ensemble(Nose-Hoover thermostat) in the context of an ab initio molecular dynamics ...
3 votes
0 answers
50 views

Can we calculate superconducting properties of materials using first-principle?

In his book Condensed Matter in a Nutshell, the late Gerald D. Mahan wrote that The calculation of a crystal's superconducting properties is not yet possible (p. 5). The book was published in 2010. ...
3 votes
0 answers
49 views

Is there any relation between electride and an electron localization function (ELF)?

I would like to know if there is any correlation between the ELF values with materials in the electronic phase, versus with the electride phase?
3 votes
1 answer
69 views

Plane wave expansion of the wavefunction for periodic material modelling

The aim is to do an electronic calculation with static nucleus with Plane wave (PW) basis functions for an infinite periodic material. The number of functions is given by the pairs of reciprocal ...
4 votes
1 answer
105 views

How to read UPF pseudopotential for ultrasoft pseudopotential simple in a fortran program

I'm currently working on calculating semiempirical local and nonlocal matrix elements for Ga. To proceed with my calculations, I need to extract specific parameters from the UPF (Unified ...
4 votes
1 answer
57 views

Original reference for gapped chiral fermion k·p model?

In eq. 1 of this reference, the authors present the following Hamiltonian for the 2-band gapped chiral fermion model that can describe many systems including various semiconductors, N-layer graphene, ...
33 votes
1 answer
498 views

Where/when did the fields of Operations Research and Spin Physics or Molecular Dynamics begin to cross-pollinate?

Operations Research is a field of mathematics in which optimal or near-optimal solutions are sought for complicated problems. In the modeling of materials, we often optimize Ising models, in which the ...
4 votes
0 answers
39 views

Where can I read about Valleytronics?

Where can I read about Valleytronics? Are there any good books or review papers or influential papers on this topic? The question was also posted at the Physics site.
5 votes
0 answers
56 views

Strongly Correlated Materials: Theoretical Frameworks, Computational Techniques, and Machine Learning Breakthroughs in Matter Modeling

This is more of an opened discussion, recommendations, and experts views on the Strongly correlated materials. Exploring the behavior of strongly correlated materials poses significant challenges in ...
3 votes
0 answers
34 views

Convex hull calculations with WIEN2k

How does one do the calculation of a convex hull with the WIEN2k code for the formation energy of alloys?
4 votes
0 answers
41 views

Gauge constraint in the definition of the Z2 invariant

Cross-posted at Physics.SE. In Fu and Kane's paper from 2006, the authors define the $\mathbb{Z}_2$ invariant for time-reversal invariant topological insulators as an obstruction to Stoke's theorem, $$...
4 votes
0 answers
67 views

How can I improve the visualization of a band structure plot for a dense supercell?

I computed the band structure of my material's supercell using Quantum ESPRESSO,but the resulting plot appears to be densely populated with bands, like in the picture bellow: Could someone provide ...
2 votes
0 answers
82 views

Why the total energy calculated with GGA and metaGGA=SCAN are so different?

Why the total energy calculated with GGA and metaGGA=SCAN are so different? My INNCAR file is ...
3 votes
0 answers
224 views

Noncollinear band structure calculation with VASP

I am trying to do a band structure calculation of a noncollinear magnetic system. I am getting results that are nowhere close to what I'm expecting. I need help checking if I am following the right ...
5 votes
1 answer
102 views

How to plot downfolded bands from DFT bands?

Once you mapped the high symmetry points from primitive cell to the super cell, you need to plot the downfolded bands. As we know in DFT output of band structure calculation we get a set of E vs k ...
4 votes
0 answers
47 views

Why, if the potential is different from the Coulomb one, but has spherical symmetry, the eigenvalues of the system are non-degenerate? [closed]

Question duplicated from here https://mathematica.stackexchange.com/questions/287433/why-if-the-potential-is-different-from-the-coulomb-one-but-has-spherical-symme and here https://physics....
2 votes
0 answers
34 views

Doping induced overall bandgap narrowing vs. bandgap narrowing achieved by localized doping induced level

Doping is an efficient strategy to narrow the bandgap of wide-bandgap metal oxides, in order to harvest more light. Let's consider the mechanism by which doping reduces the bandgap of a metal oxide ...
3 votes
1 answer
88 views

Symmetry for the low-energy effective model of Weyl semimetal

The low-energy effective model for Weyl semimetals (WSM) at a single Weyl point can be written as: $$H_{w}=\chi \vec{k} \cdot \vec{\sigma}, \tag{1} $$ where $\chi$ is the chirality index, $\vec{k}$ is ...
8 votes
1 answer
496 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 ...
4 votes
0 answers
158 views

If the system respects time-reversal symmetry, does the T-even anti-symmetric conductivity tensor indicate a dissipationless transport?

In this paper, the authors discuss the three response relations or Ohm's law for spin/charge transport. The first one is the spin Hall effect described by: $$J_j^i=\sigma_{s}\epsilon_{ijk}E_k \tag{1},$...
4 votes
0 answers
145 views

Help with Mathematica for optimizing a Gaussian basis set for a hydrogen atom in a magnetic field

This is a follow-up to my previous question: Optimal Gaussian basis set for hydrogen atom in magnetic field Brief description of the problem I would like to find the ground and excited states of the ...
7 votes
1 answer
168 views

Optimal Gaussian basis set for hydrogen atom in magnetic field

Copy from here https://mathematica.stackexchange.com/questions/285044/optimal-basis-set-of-gaussian-functions-for-describing-a-quantum-system This question arose during the discussion of the previous ...
8 votes
2 answers
241 views

How to get the directives of a slurm for my Quantum ESPRESSO calculations?

Context I saw some examples of SLURM scripts on the internet like the one below: ...
5 votes
1 answer
804 views

How to restart an interrupted Quantum ESPRESSO calculation?

I was doing a vc-relax calculation and after 1 day the calculation suddenly stopped. Is there a way to restart it from previous interrupted calculation of do I have to restart from the beginning?
6 votes
1 answer
121 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?
5 votes
0 answers
56 views

Presence/absence of topologically protected edge states on the boundary of two topological insulators [closed]

A normal insulator is the same as vacuum because one can change the band structure from one to another without closing the gap, but for topological insulators (talking about 2D TI) like 1T'-TMDs or ...
7 votes
1 answer
202 views

Geometry optimization: nuclear coordinates vs lattice parameters

I would like to know whether, at least in principle, minimization of energy with respect to nuclear coordinates leads to the same result as minimization of cell energy with respect to lattice ...
14 votes
1 answer
258 views

What are differences between Mott and Anderson transitions?

Can anyone please explain the differences between Anderson and Mott insulator-metal transition? I found some information in the book named "The_Physics_of_Amorphous_Solids".
3 votes
1 answer
100 views

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

I try to reproduce the dielectric function as the picture bellow using Yambo code but the values that I have found in y-axis are so much bigger [-1000,1500] compared to literature. I generated the scf ...
3 votes
0 answers
66 views

Kohn anomaly and avoided crossing (or anticrossing/level repulsion) [closed]

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-...
5 votes
2 answers
1k views

How to increase the number of CPUs in my computer?

I'm running my calculations using Quantum ESPRESSO on a 10th generation i7 computer (Dell) with Ubuntu. When I run any calculation using the command ...
6 votes
0 answers
55 views

Is it possible to evaluate rotational and vibrational partition functions for diffusion in the Eyring Theory of Absolute Rates? [closed]

Let us consider the usual expression for Diffusion processes and diffusion coefficients in the Eyring's theory: $$D=\lambda^2k = \lambda^2 \frac{k_BT}{h}\frac{\Omega_\ddagger}{\Omega}e^{-\frac{\...
1 vote
1 answer
69 views

Is it possible to define a property like strain to characterize the structural change?

Lets suppose that I have an atom chain like system 1 below. Now, some interaction made one atom to move out of the chain, like shown in system 2 (the moved atom remains bounded but in another position)...
8 votes
0 answers
126 views

What are some types of topologically-relevant band degeneracies in contemporary 2D condensed matter research? [closed]

In the study of 2D condensed matter systems, I have seen several kinds of band degeneracies. I call 'bands' the eigenvalues to the time-independent Schrodinger equation, solved over 2D k-space. By '...
1 vote
0 answers
36 views

Invariance of magnetic susceptibility when rotating a tight-binding Hamiltonian [closed]

We know the magnetic susceptibility for a non-interacting tight-binding model has the Lindhardt form, for which I express as product of matsubara Green's functions $$\chi^{(0)}(q,\omega)=-\beta\sum_{k,...
2 votes
0 answers
107 views

How to create the supercell to simulate a disordered solid solution? [closed]

I am trying to simulate the DOS of a disordered semiconductor (Cd0.5Zn0.5S), my plan is to get the .cif file of CdS first, and build a supercell, then I should ...
3 votes
2 answers
70 views

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 ...
4 votes
1 answer
147 views

Is there any useful application to estimating the expectation value for an Ising model without magnetic field?

In the same line of thoughts as this post, I am trying to understand better in which cases quantum computers could be useful to simulate materials under some constraints on what the quantum computer ...
8 votes
2 answers
292 views

Are there interesting applications of estimating the energy for generalizations of the Heisenberg model?

I consider that $H$ is a Hamiltonian describing a quantum system of $n$ spin-1/2 particles (or qubits). I assume it can be written as (the $\alpha_k^i$ are real coefficients): $$\tag{1}H=\sum_{i=1}^3 ...
5 votes
2 answers
164 views

What's the completeness relation of Bloch band?

Bloch's theorem can be stated as: $$ |\Psi_{n\vec{k}}\rangle=e^{i\vec{k}\cdot\vec{r}}|u_{n\vec{k}}(\vec{r})\rangle \tag{1} $$ where $|\Psi_{n\vec{k}}\rangle$ is the solution of single electron ...
5 votes
0 answers
181 views

About the mechanism of opening of the band gap in topological insulator with the inclusion of SOC [closed]

When we work on the topological insulator (protected by time reversal symmetry ), it is often said that the SOC is the main ingredient because it is a way to open a gap when the band inversion present....
5 votes
0 answers
53 views

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-...
4 votes
1 answer
276 views

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 ...