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Questions tagged [condensed-matter]

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A problem to simulate the kinetic energy operator using some field going through a crystal

We know about a differentiation and integration operations and also other ones can be simulated by an analog way using electric circuits with operational amplifiers (here are articles of the ...
SFriendly's user avatar
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5 votes
1 answer
74 views

Can conventional unit cell have higher symmetry than primitive cell for the same crystal?

This question arises from the last sentence of the first paragraph (see here) of the section "Formalism". If primitive cell can have lower symmetry, why don't the DFT results using these two ...
AbPhys's user avatar
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4 votes
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36 views

Phonon dispersion calculation of graphene with ASE

I'm trying to use the package ase.phonons to calculate the dispersion relation bands and the DOS, I followed the example of the documentation for Al and went well for the diamond case. For some reason,...
Rob Lut's user avatar
  • 41
5 votes
0 answers
38 views

About alignment of 2D monolayer band structures

I need to do the alignment of band structures of one 2D monolayer. I have created some vacancies in the 2D monolayer using VASP and calculated the band gap values (GGA) corresponding to different ...
Poonam Sharma's user avatar
7 votes
1 answer
53 views

Force fields for generating **Co3O4 and Fe3O4 structures in LAMMPS

I am working on a project that requires generating a large dataset of Co3O4 and Fe3O4 structures under various temperatures and pressures using LAMMPS. The structures will be used for training machine ...
li jiwei's user avatar
2 votes
1 answer
44 views

Structural stability of Graphene

is it acceptable if I came up with around -8.5ev/atom for cohesive energy of graphene?, Literature is in the range 7.3-7.9 ev/atom The formula used for cohesive energy calculation Codes I have used ...
Thejan Hasaranga's user avatar
3 votes
0 answers
38 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 ...
Joyal sunny's user avatar
3 votes
0 answers
50 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. ...
Roman Punk's user avatar
6 votes
0 answers
57 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 ...
Qwertuy's user avatar
  • 181
2 votes
1 answer
68 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 ...
Rubi Agrawal's user avatar
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 ...
Peter Pien's user avatar
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 $n = 0$...
user192399's user avatar
2 votes
1 answer
233 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 ...
Rubi Agrawal's user avatar
1 vote
0 answers
94 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: ...
Meifeng WANG's user avatar
3 votes
0 answers
51 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. ...
Abdul Muhaymin -Free Palestine's user avatar
4 votes
0 answers
40 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.
Rich Hard Fine Man's user avatar
3 votes
1 answer
71 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 ...
mle's user avatar
  • 1,031
4 votes
1 answer
121 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 ...
Raj Kumar Paudel's user avatar
5 votes
0 answers
58 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 ...
Jaafar Mehrez's user avatar
3 votes
0 answers
36 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?
Moussa Rabah's user avatar
4 votes
0 answers
43 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, $$...
Sounak Sinha's user avatar
4 votes
0 answers
70 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 ...
Camilla's user avatar
  • 2,169
2 votes
0 answers
85 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 ...
babak ab's user avatar
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....
Mam Mam's user avatar
  • 253
2 votes
0 answers
36 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 ...
meTchaikovsky's user avatar
3 votes
0 answers
246 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 ...
Nani Janelidze's user avatar
4 votes
0 answers
147 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 ...
Mam Mam's user avatar
  • 253
8 votes
2 answers
250 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: ...
Camilla's user avatar
  • 2,169
5 votes
1 answer
904 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?
Camilla's user avatar
  • 2,169
6 votes
1 answer
142 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?
chemdamned's user avatar
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 ...
chemdamned's user avatar
7 votes
1 answer
171 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 ...
Mam Mam's user avatar
  • 253
5 votes
0 answers
59 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 ...
Runnong Zhou's user avatar
4 votes
1 answer
110 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 ...
Camilla's user avatar
  • 2,169
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-...
AbPhys's user avatar
  • 741
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 ...
Camilla's user avatar
  • 2,169
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{\...
Giuseppe Basile's user avatar
4 votes
1 answer
58 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, ...
TribalChief's user avatar
  • 2,361
8 votes
1 answer
519 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 ...
franz's user avatar
  • 297
4 votes
0 answers
171 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},$...
Jack's user avatar
  • 15.2k
3 votes
1 answer
90 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 ...
Jack's user avatar
  • 15.2k
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)...
Camps's user avatar
  • 23.4k
5 votes
1 answer
104 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 ...
Alpha_Roy's user avatar
  • 123
3 votes
0 answers
52 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?
Sak's user avatar
  • 979
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,...
Zhihui's user avatar
  • 111
2 votes
0 answers
109 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 ...
Jack's user avatar
  • 2,057
3 votes
2 answers
71 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 ...
Alpha_Roy's user avatar
  • 123
4 votes
1 answer
148 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 ...
Marco Fellous-Asiani's user avatar
8 votes
2 answers
293 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 ...
Marco Fellous-Asiani's user avatar
5 votes
2 answers
181 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 ...
Jack's user avatar
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