Questions tagged [condensed-matter]
For all matters related to condensed matter physics.
31
questions
12
votes
1answer
73 views
What are the physical consequences of adding a constant to the diagonal of the effective Hamiltonian of monolayer materials?
Effective Hamiltonians modeling many-layered materials are often tuned using some sort of bias voltage. For instance, in a $4\times 4$ Hamiltonian matrix to describe biased bilayer graphene using some ...
3
votes
0answers
29 views
Doubt in Raoultian and Henrian Standard State
$Si(liq)=Si_\text{(1 wt% Fe)}$
Can you describe what is going on here?All that they ask for is change in Gibbs free energy for the process.I am completely unable to figure why this particular model is ...
7
votes
1answer
54 views
Where is this extra plane coming from?
Why are there solid lines drawn connecting the solid circles after twinning has taken place? Ideally, that explains a real plane, isn't it? But why are we going to get a plane out of nothing if we ...
9
votes
1answer
59 views
How to predict new Half Metallic materials with higher degree of spin polarization?
Using DFT calculations, how one can predict the new half metallic materials with higher degree of spin polarization. I want to know the steps which have to be followed in prediction of new materials. ...
10
votes
2answers
224 views
How to choose pseudopotential for DFT calculations in Quantum ESPRESSO?
I am a beginner and newly started running DFT calculations to find out the electronic band structure of certain materials in Quantum ESPRESSO. But we have to select the pseudopotential for running the ...
12
votes
3answers
335 views
External magnetic field in VASP?
I have never found any tags or documentation regarding external magnetic field in VASP but in different well known published articles$^1$, the implementation of the external magnetic field by VASP has ...
8
votes
1answer
206 views
How to perform virtual crystal approximation calculations in VASP?
Can someone share appropriate tags and methods to perform virtual crystal approximation calculations in VASP?
9
votes
1answer
174 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 ...
4
votes
1answer
45 views
How to simulate a furnace computationally
I am trying to synthesize MoSe$_2$ crystals in a furnace with two temperature zones.
The problem is that the oven is not very wide, so the temperature of the hottest zone influences the temperature of ...
9
votes
0answers
40 views
Symmetry of glide planes [closed]
I am trying to understand the symmetry elements of space group number 194 (P$6_3$/mmc), which is hexagonal and has 24 symmetry operations.
In the table of symmetry operations it says that it has three ...
9
votes
0answers
52 views
Structural biology vs condensed matter prediction
I have two main modeling research lines: one related to structural biology (including rational drug design, de novo design, polymorphism, etc.) and the other one related to condensed matter (...
12
votes
2answers
88 views
What are real examples where fractals were used in Matter Modeling?
A fractal is, accordingly Oxford English Dictionary:
A curve or geometric figure, each part of which has the same statistical character as the whole. Fractals are useful in modeling structures (such ...
13
votes
1answer
138 views
Can we “invert” Density Functional Theory through sufficiently accurate experiment?
The famous Hohenberg-Kohn theorems say that there is a one-to-one mapping between the many-body Hamiltonian, $\mathcal{H}$, of a solid and its ground-state electron density $\rho(\mathbf{r})$. As far ...
11
votes
1answer
128 views
What are some codes available for Dynamical Mean Field Theory (DMFT)?
One particularly field of matter modeling is that of strongly correlated materials, heavy-fermion compounds with partially filled 4f or 5f orbitals. In brief, these are materials whose complex ...
5
votes
1answer
47 views
Property related with Berry curvature: $\Omega_{n,\mu\nu}=-\Omega_{n,\nu\mu}$
I read in David Vanderbilt's book named "Berry Phases in Electronic Structure Theory - Electric Polarization, Orbital Magnetization and Topological Insulators" the definition of Berry ...
16
votes
1answer
938 views
How to understand 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 ...
12
votes
1answer
123 views
Real space projection vs reciprocal space projection in DFT calculations
When doing VASP calculations for large cells, we get a warning:
"You have a (more or less) 'large supercell' and for larger cells it
might be more efficient to use real space projection ...
17
votes
1answer
162 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 ...
12
votes
2answers
175 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 ...
14
votes
2answers
495 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 ...
8
votes
1answer
178 views
2D Brillouin zone generator
There are several pages where you can find scripts/simulations to generate the first Brillouin zone for square and hexagonal 2D lattices.
I wonder if there is a tool to generate the Brillouin for ...
15
votes
0answers
87 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^\...
10
votes
1answer
149 views
What is the difference between U(1) and O(2) symmetry?
To my understanding, they both refer to circular symmetry. I know U(1) is the complex plane, and I think O(2) is real numbers. I have seen them used more or less interchangably, but is there actually ...
20
votes
2answers
315 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 ...
16
votes
1answer
59 views
What are good resources to study crystallographic defects in different dimensional systems and their topological dimensionality?
I wonder if there are any books or resources that may address one or more of the following questions:
What kinds of defects are important for topology? Especially crystallographic defects.
How do ...
20
votes
1answer
136 views
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,...
17
votes
1answer
99 views
What exactly is a topological insulator and how to recognize one from band structure?
Four years ago, the Nobel Prize in physics was awarded for "for theoretical discoveries of topological phase transitions and topological phases of matter." In line with this, I heard of topological ...
20
votes
1answer
117 views
What is the importance of electron interaction on dielectric response of crystals?
After obtaining the Kohn-Sham orbitals from a plane-wave-based self-consistent-field calculation, the dipole matrix elements could be calculated in order to determine electro-optical properties such ...
16
votes
1answer
87 views
Functionals/basis sets optimized with respect to properties?
In general (at least for molecular calculations) basis sets and DFT functionals are fit to some high level calculation or experimental energy. It is speculated that an accurate energy will result in ...
21
votes
2answers
163 views
Is there a list of all universality classes for phase transitions with examples of each?
I've often had this problem: I have a model that has a phase transition in it, but I don't know what universality class it falls into or what the universality class is called.
Is there anywhere on ...
24
votes
0answers
198 views
Where/when did the fields of Operations Research and Materials Modeling begin to cross-pollinate? [closed]
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 ...
