9
votes
Difference between "electrical" and "electronic"?
Electric conductivity can be created by particles other than electrons (like ions in solution), or by electrons moving in some more sophisticated way than straightforward (hole conductivity in ...
9
votes
Accepted
Can deformation potential theory be applied to 2D and 1D systems?
Deformation potential theory is almost always used to study 2D materials. The first line of the abstract of the original Bardeen-Shockley paper mentions "deformations of the crystal lattice"....
- 33.6k
8
votes
What is signified by the properties of the electronic band structure?
The band structure determines the dispersion relation for the electrons within the material, the E(k) relation. Its gradient (the inverse of it, to be more precise) is related to the effective mass of ...
- 3,238
7
votes
Mobility and chemical potential
In this case, $\mu$ refers to the chemical potential. The reason it is given as $\mu-E_f$ is simply to highlight that the "zero" has been set to the Fermi-level of the reference calculation (...
- 6,647
7
votes
Tools for electronic transport calculations
Nanodcal
Nanodcal is implemented with real space density functional theory (DFT) using the Keldysh nonequilibrium Green’s function formalism (NEGF). It can calculate nonlinear and non-equilibrium ...
- 8,922
7
votes
Accepted
Transiesta output through a single gold atom
With a single atom there might be leakage current. Probably, if you had more Au atoms the transmission would be fully suppressed.
The 4 eV peak is likely close to a van-Hove singularity of the ...
- 3,084
6
votes
Tools for electronic transport calculations
TranSIESTA (SIESTA)
TranSIESTA is an LCAO code (similar to OpenMX) which is implemented in fortran. The NEGF methods here allows N>=1 -terminal calculations as well as real space self-energies (for ...
- 3,084
6
votes
Tools for electronic transport calculations
OpenMX
OpenMX is another LCAO code (similar to SIESTA) which is implemented in C. It also implements the NEGF formalism similar to TranSiesta.
It is open source.
- 3,084
6
votes
Theories for electronic transport calculations
Boltzmann Transport
Transport of electrons in the presence of electric field and magnetic field can be described uisng Boltzmann transport equation. There are Classical and semi-classical formalisms ...
- 8,922
6
votes
Accepted
Mobility and chemical potential
If you go to the definition of the Seebeck coefficient ($S$) you will find:
$$S = \frac{{e{k_B}}}{\sigma }\int {d\varepsilon \left( { - \frac{{\partial {f_0}}}{{\partial \varepsilon }}} \right)} \Xi \...
- 22.3k
6
votes
Evaluating Seebeck coefficient using DFT
I'm posting this here as an answer so that if anyone else runs into the same problem, they can get it clarified.
After searching endlessly (because the SIESTA to BoltzTraP2 interface provided by the ...
- 2,603
6
votes
Difference between "electrical" and "electronic"?
The adjective
electric refers to the current (a technical quantity), while electronic, especially if used in contrast, refers to the fermionic particle.
- 346
6
votes
Accepted
Would it be appropriate to use a Van der Waals-DFT approximation in Quantum ESPRESSO to study the properties of my material (p-type semiconductor)?
No, van der Waals functionals would not be appropriate for this type of system - at least, not normally.
Most semiconductors of interest are strongly bonded 3D materials, with covalent bonds and ...
- 6,647
5
votes
Accepted
Meaning of Kronecker Product in Transport Theory behind BoltzTrap2
Yes, that operation yields a matrix result. The charge conductivity $\sigma$ is also a matrix (often called the conductivity tensor) so the equation looks correct. It may be clearer if written out ...
- 4,711
5
votes
Accepted
How to evaluate the electron relaxation time of nanostructures computationally
The electronic relaxation time cannot be predicted from the band-structure alone, because it depends on additional physics. The dominant mechanism for electron relaxation in materials is usually the ...
- 6,647
5
votes
Tools for electronic transport calculations
I provide more information about the tools for quantum transport.
KITE
KITE is an open-source Python/C++ software suite for real-space tight-binding (TB) simulations of electronic structure and bulk ...
- 14.9k
5
votes
Quantifying electronic overlap?
I recommend the use of Multiwfn package. This software is free with Windows/Linux versions. It uses the wave function calculated from other software.
From the site:
Briefly speaking, Multiwfn can ...
- 22.3k
4
votes
Quantifying electronic overlap?
By the "metal cores", If you're referring to the overlapping of wave functions of electrons of metal ions separated by a distance, then you can in principle use quantum ESPRESSO to get some ...
- 4,448
4
votes
The relation between applied voltage and band gap in Transport calculation (DFT+NEGF)
When dealing with open boundary problems with a bias, the full system Fermi-level is somewhat ill-defined. Consider that the left electrode is in equilibrium at its $\mu_L= e_F + V/2$ and the right at ...
- 3,084
4
votes
Accepted
Transiesta geometry optimization
Generally it would be sufficient to optimize the geometry in siesta since that geometry will likely be the same geometry as for V=0. The reason should be straightforwardly understood if one thinks ...
- 3,084
4
votes
Accepted
Could I simulate the applied voltage on the electrode by adding extra electrons in the system?
You have found for yourself that it is not difficult to reduce water if you throw a suitably overwhelming number of electrons at it, but you're also skeptical that this reflects realistic experimental ...
- 2,673
4
votes
Accepted
I/V curve on Transiesta paper
The graph in question is this:
The article describes the importance of correctly simulating the self-consistent solution for temperature gradients (not bias).
Generally, NEGF software have used the ...
- 3,084
3
votes
Accepted
How can I get the projected density of states within the Green's function method?
I believe that you can get what you want using the spectral density,
$$\rho({\bf r},{\bf r'},E) = -\frac{1}{\pi}{\rm Im}[G({\bf r},{\bf r'},E)]\tag{1}$$
Then the total density of states would be an ...
- 46
3
votes
Accepted
What is the transiesta+tbtrans procedure?
You got it a bit wrong.
TranSiesta
This program (a sub-module in Siesta) self-consistently solves the NEGF equations to calculate the system at a finite bias. Upon self-consistency, the Siesta program ...
- 3,084
3
votes
Accepted
Empty orbitals in Transiesta
There is per see nothing to prohibit the use of empty orbitals in TranSiesta calculations. In fact, in some cases they are very much required (vacuum spaces between STM tip and sample for instance).
...
- 3,084
3
votes
Accepted
How to simulate the electron transfer during OER with AIMD?
When a bias is applied to an electrode that drives OER, the bias is versus a counter electrode. The counter electrode is a macroscopic distance away, and I have yet to see an AIMD simulation that ...
- 763
3
votes
Theories for electronic transport calculations
I believe the plane-wave codes can utilise a form of the wave-function matching technique to calculate device modes coupled to scattering states in the bulk parts, see e.g. http://dx.doi.org/10.1103/...
- 3,084
3
votes
Accepted
Are there tools to calculate the electrical conductivity of large (>1000 atom) nanostructures?
There are a lot of detailed considerations when computing electronic transport, but in general the answer is "yes", provided you can calculate (or estimate) a model Hamiltonian. For example, ...
- 6,647
3
votes
Are there tools to calculate the electrical conductivity of large (>1000 atom) nanostructures?
Yes. Take a look at SIESTA: the "Spanish Initiative for Electronic Simulations with Thousands of Atoms". Love that name.
It is much more efficient than the plane-wave DFT codes for this type ...
- 93
3
votes
Accepted
Transiesta calculation at non-zero bias
In versions <= 4.0 the old flags:
TS.biasContour.Eta
TS.biasContour.NumPoints
were used to determine the imaginary $\delta$ of the Green function calculation ...
- 3,084
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