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Questions tagged [condensed-matter]

For all matters related to condensed matter physics.

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17 votes
1 answer
5k views

How to understand the time-reversal symmetry in graphene?

A lot of references say that the Dirac cone in graphene is protected by inversion and time-reversal symmetries. How can one understand this statement? How can one show explicitly that the gapless ...
JensenPang's user avatar
  • 2,883
13 votes
2 answers
976 views

How to convert Unified Pseudopotential Format (UPF) into Ultrasoft Pseudopotential (USPP) format?

I am working on DFT code having plane wave along xy axis and bspline in z direction. For calculating the properties of TMD materials, spin orbit coupling must be included but i did not find fully ...
Raj Kumar Paudel's user avatar
33 votes
1 answer
499 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 ...
Nike Dattani - No Free Time's user avatar
19 votes
2 answers
392 views

What significant matter modelling methods are implemented in commercial software, for which there is no freeware alternative?

There is an ever-growing list of freeware and open-source software for solid-state physics and quantum chemistry. But many commercial programs still thrive, even in 2020, and their cost can be in ...
Matthew W. Noble's user avatar
19 votes
1 answer
2k views

Difference between potential energy, free energy and Coulomb energy in solid state physics

I often encounter terms such as (Helmholtz, Gibbs) free energy, potential energy and total energy when describing the energy of a physical system at atomic level. Sometimes I stumble upon Coulomb ...
Achintha Ihalage's user avatar
17 votes
1 answer
581 views

How to find the projected Hamiltonian for lowest flat-band in general?

In [1], starting with the bosonic Hamiltonian (Eqn. 1) for the dice lattice model with half flux density (with Ahronov-Bohm phases incorporated), \begin{equation} H=-t\sum_{\langle j,\mu\rangle}(a^\...
Siddhant Singh's user avatar
14 votes
2 answers
622 views

How much does the initial geometry affect the final geometry in optimization calculations?

This might be a stupid question but to what extent will the initial configuration of a bulk phase geometry optimization calculation affect the final geometry? Most places say to start with ...
Cavenfish's user avatar
  • 1,222
13 votes
2 answers
979 views

How can we say that the KS equation is describing a noninteracting many-electron system?

Based on HK's two theorems, the density functional theory was built. Because one can't find the universal energy functional $F_{HK}[n(r)]$, Kohn and Sham further proposed the Kohn-Sham ansatz: mapping ...
Jack's user avatar
  • 15.1k
12 votes
1 answer
486 views

How to start with structural defects in monolayer?

First of all, thank you for your help! You are so helpful every time. I would like to calculate the influence of the structural defects on the electronic structure in the HfS2 monolayer. With VESTA ...
M_Fisher's user avatar
  • 631
11 votes
1 answer
350 views

How to use wavefunctions/density to determine which orbitals lead to edge states?

I have a large matrix for a 1D zigzag edge model of an otherwise $3\times 3$ tight-binding Hamiltonian (3 basis functions, each corresponding to an atomic orbital), involving the variable $k_x$. The ...
TribalChief's user avatar
  • 2,351
9 votes
0 answers
92 views

How does infinite DMRG work? [duplicate]

iDMRG or infinite-size density matrix renormalization group, is a common technique in condensed matter. It seems that usually people believe that it reliably captures infinite-size behavior. I have ...
taciteloquence's user avatar
8 votes
0 answers
119 views

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 ...
TribalChief's user avatar
  • 2,351
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
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 ...
Mam Mam's user avatar
  • 253
6 votes
1 answer
72 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 ...
TribalChief's user avatar
  • 2,351