Questions tagged [electronic-transport]

Questions about electron transport.

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Siesta - Segmentation fault error

I am trying to perform a scattering region calculation but I get this error : (from .err file) ...
Youssef Chlikhy's user avatar
6 votes
0 answers
39 views

Can Boltzmann transport equation as implemented in Boltztrap software be considered first-principles?

According to the documentation of Boltztrap, the electrical conductivity is given in the following equation: $$\sigma=\frac{1}{k_BT}\int_{-\infty }^{\infty }f(1-f)\mathrm{\textbf{X}}(\varepsilon)d\...
Jaafar Mehrez's user avatar
4 votes
1 answer
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How can I solve the error in TRANSIESTA calculations? [duplicate]

Recently, I've been trying to calculate the transmission coefficients for the molecular junction (Au lattice - molecule - Au lattice) using SIESTA, TRANSIESTA, and TBtrans. As you know, the procedure ...
Jonghwan Lee's user avatar
3 votes
1 answer
49 views

The Dynamic Constant Matrix for the Green Function in the Thermal Conductance Calculation

When computing the thermal transmission coefficient, the green function needs to be computed first; for example, $G^{R}_{scattering\:region}=\left[\left(\omega+i0^{+}\right)^{2}I-D\right]^{-1}$, where ...
Kieran's user avatar
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2 votes
1 answer
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Transiesta scattering calculation not converging

I am trying to perform electron transport calculations. At the level of the scattering region calculations, I have noticed that the values of energies are no longer changing: ...
Youssef Chlikhy's user avatar
2 votes
0 answers
60 views

Difference of the Transmission Coefficient between Thermal and Charge Conductance by Nonequilibirum Green Function Method

The equation 57 in the reference [Jian-Sheng Wang, Jian Wang and J. T. Lu, Quantum thermal transport in nanostructures, Eur. Phys. J. B 62, 381 (2008)] explains the the transmission coefficient for ...
Kieran's user avatar
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1 answer
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Transiesta with siesta version 4.1.5 not converging

Good evening everyone, With previous Transiesta versions, we would not have issues with finding the transport involving graphene. However, this was not the case with the latest version. We tried: ...
abed haidar's user avatar
3 votes
1 answer
63 views

Implemetation of NEGF in TranSIESTA

I have a general query regarding NEGF approach: In TranSIESTA code, when self-energy of the electrodes is calculated, does it require the coupling elements of the electrode with the central scattering ...
sushil's user avatar
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5 votes
1 answer
108 views

Effect of carrier concentration on electrical conductivity

As per my understanding, the electrical conductivity of a material can be expected to increase with the increased carrier concentration. However, beyond a certain (extreme) point, the electrical ...
PBH's user avatar
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6 votes
1 answer
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Variation of Conduction band minimum and valence band maximum with applied strain in semconductors

I have been using the Deformation Potential theory to evaluate the electron scattering rates in nanomaterials. In each case, I was under the impression that the Conduction Band Minimum (CBM) and the ...
PBH's user avatar
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3 votes
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Quantum ESPRESSO vs AMS [closed]

Both Quantum ESPRESSO and AMS (Amsterdam Modeling Suite) can be used to perform simulations of the materials and their properties. What are the differences between AMS and Quantum ESPRESSO? Is it ...
Zeina 's user avatar
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Transport calculations with AMSET package [closed]

I am trying to calculate transport properties using the AMSET package (with VASP), to be able to calculate the electron relaxation time. My system is a monolayer of graphene doped with isoelectronic ...
Laura's user avatar
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4 votes
1 answer
118 views

Inverse Matrix Calculation

I am working on the charge transport calculation, based on the non-equilibrium green function method, for the Hamiltonian with the non-orthogonal basis. Suppose $H$ and $S$ are the Kohn-Sham ...
Kieran's user avatar
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7 votes
0 answers
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Calculation of charge transport with the non-orthogonal basis Hamiltonian based on the non-equilibrium Green's function method

I am thinking about one question. If the Hamiltonian matrix is based on the non-orthogonal basis, how to compute the charge conductance with the Non-Equilibrium Green's Function (NEGF) method. Suppose ...
Kieran's user avatar
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5 votes
1 answer
76 views

Post-processing in TBTrans

I would like to write a simple code calculating Conductance and Seebeck coefficients in function of the chemical potential. To do this, I would like to use the equation: $$L_n(\mu, T)=\frac{2}{h}\int ...
Laura's user avatar
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2 votes
0 answers
59 views

Figure-of-merit with Transiesta/TBtrans [closed]

Would it be possible to calculate the figure-of-merit: $$ZT =\frac{S^2\sigma}{\kappa}T,\tag{1}$$ with Transiesta and TBTrans? If not, which other programs can be used? I've only read about Gollum.
Laura's user avatar
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3 votes
0 answers
21 views

Calculation of Seeback coefficient on Transiesta [closed]

From the paper Improvements on non-equilibrium and transport Green function techniques: The next-generation transiesta, and in particular in figure 10b, an I/V curve is reported. I understand that ...
Laura's user avatar
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5 votes
1 answer
80 views

I/V curve on Transiesta paper

In the paper 'Improvements on non-equilibrium and transport Green function techniques: The next-generation transiesta and in particular in figure 10b, the I/V curve of a specific model is reported. ...
Laura's user avatar
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3 votes
1 answer
80 views

Could I simulate the applied voltage on the electrode by adding extra electrons in the system?

I try to use molecular dynamics to simulate the half-reaction of the H2O reduction on the Pt cluster. Is it possible to add extra electrons in the system to simulate the reduction process? The Pt ...
Jack's user avatar
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3 votes
1 answer
224 views

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)?

I want to study the structural, optical, electronic and transport properties of my material that contains Cu atoms using Quantum ESPRESSO. I tried so many approximations but every time I face an issue ...
Camilla's user avatar
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4 votes
1 answer
81 views

Any software that can model eddy currents?

Is there any software on metals that can predicts orbital or induced currents in metals in the presence of a magnetic field or electromagnetic waves?
Jellium mind's user avatar
3 votes
1 answer
211 views

How to add the scissor operator in Quantum ESPRESSO input?

I want to calculate the optical, transport and electronic properties of my material. GGA underestimate the bandgap. I tried GGA+U but the bandgap is still underestimated and also when I tried to use ...
Camilla's user avatar
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3 votes
1 answer
64 views

Why can graphene nanoribbons be safely used as electrdes, despite having a finite band gap?

I was following the following this tutorial. As far as my understanding goes, one should use bulk-like metallic electrodes to avoid problems with screening and Fermi-level definition. Can someone ...
Laura's user avatar
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4 votes
1 answer
153 views

How to set the different left and right electrodes of transiesta?

I am using transiesta, which works when the left and right electrode structures are consistent. Now I want to know how to set up the different left and right electrodes, how I should prepare the ...
peng's user avatar
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4 votes
0 answers
70 views

How to locate HOMO-LUMO molecular orbitals in Transmisson and PDOS graphs? [closed]

I have done TBtrans calculations using SIESTA (v4.0.2) and plotted transmission, as well as PDOS Vs Energy graphs. I want to know how to locate HOMO-LUMO MOs in those graphs (or) how can I say which ...
Shanmuka Rao's user avatar
3 votes
1 answer
88 views

Transiesta warning (Error on inverting X6/C7 with error: 1)

I have run into trouble when I try to do transport calculations in TranSIESTA. I got this message in the output file, before reaching convergence: ...
Hananab's user avatar
  • 369
2 votes
0 answers
64 views

Current value changes with contour values in SIESTA [duplicate]

My question is related to the topic solved here: DOS calculation with TBTrans Here, in the answer, the imaginary contour manipulation is proposed to smooth the DOS. I noticed, however, that doing this ...
Laura's user avatar
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1 vote
0 answers
31 views

Transiesta electrodes with GNR structures [closed]

As far as I understand, it would be better to use metallic electrodes in a Transiesta calculation and avoid the usage of semiconducting electrodes. It should be related to the bad screening of the ...
Laura's user avatar
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2 votes
1 answer
76 views

Transmittive states plotting in TBTrans

I have been using transiesta and TBTrans to calculate the transmission curves of some materials. Could I theoretically compare the Transmission states with the states in the Density of States and the ...
Laura's user avatar
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3 votes
1 answer
148 views

DOS calculation with TBTrans

I calculated the Transmission curves and the Density of States using TBTrans. In particular, if I have pristine graphene (just for the sake of the example), I obtain as Transmission curve and DOS ...
Laura's user avatar
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1 vote
0 answers
31 views

Conductance and Seeback coefficient calculations with tbtrans [closed]

Like the title says, in TranSiesta I can easily calculate the transmission curves. I know that it is related to the conductance. However, how can I calculate the conductance with tbtrans? Moreover, to ...
Laura's user avatar
  • 1,197
3 votes
1 answer
99 views

Transiesta calculation at non-zero bias

I have followed the transiesta tutorials regarding calculations with different bias. I am now using a similar input for my calculations. However, I found these input parameters ...
Laura's user avatar
  • 1,197
4 votes
1 answer
96 views

Transiesta geometry optimization

Reading the transiesta manual, I understand that it would be sufficient to optimize the structure within siesta and then use the result for a transiesta run. However, I have also read that it would be ...
Laura's user avatar
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5 votes
1 answer
157 views

How to simulate the electron transfer during OER with AIMD?

I am trying to simulate the electron transfer from adsorbed H2O molecule to the electrode with AIMD. I guess I need to set up an external electric field, so the electron inside the H2O molecule would ...
Jack's user avatar
  • 2,027
2 votes
1 answer
159 views

Transiesta procedure when relaxing the structure

As the title says, I'm interested in performing Transiesta calculations with a device region that needs to be optimized. I read the slides reported here: https://departments.icmab.es/leem/...
Laura's user avatar
  • 1,197
4 votes
1 answer
482 views

What is the transiesta+tbtrans procedure?

I have tried to run some calculations on transiesta/tbtrans with a non-zero voltage. I started with a zero voltage calculation and copied the .TSDE file to run a calculation with V=0.25. However, I ...
Laura's user avatar
  • 1,197
5 votes
1 answer
90 views

Empty orbitals in Transiesta

I have noticed some difficulties in converging Transiesta calculations when including empty orbitals in the basis set, particularly when a non-zero bias is applied. In particular, I have tried to ...
Laura's user avatar
  • 1,197
3 votes
1 answer
49 views

When we can justify the response to be hold in terms of symmetry?

In this paper, the authors argue the following response relation $$j_a=\sigma_{abc}E_bE_c \tag{1}$$ can occur in systems with $\mathcal{P}\mathcal{T}$-symmetry with $\mathcal{T}$ the time-reversal ...
Jack's user avatar
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4 votes
1 answer
212 views

The relation between applied voltage and band gap in Transport calculation (DFT+NEGF)

Hello Dear StackExchange Comunity, Based on some interesting papers related to quantum transport calculation (Transiesta published paper...), the voltage applied in the device shifts the Fermi level ...
Hananab's user avatar
  • 369
6 votes
2 answers
314 views

How can I get the projected density of states within the Green's function method?

I have this Green's function matrix $G^r= (E \mathbb{I} - \hat{H})^{-1}$ in the $|\textrm{site}\rangle\otimes|\textrm{orbital}\rangle\otimes|\textrm{spin}\rangle$ Hilbert space, and I am curious if ...
jazzloaf's user avatar
6 votes
3 answers
3k views

Difference between "electrical" and "electronic"?

I found that people often measure "electrical conductivity", but some may say "electronic conductivity". Can anyone explain the terms "electrical" and "electronic&...
Binh Thien's user avatar
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4 votes
0 answers
129 views

Is it possible to obtain the current-voltage characteristic for a crystal using the Hartree–Fock (or DFT) calculation? [closed]

In continuation of the question of obtaining an electrical conductivity tensor (ECT) from the “first characteristics”, will my following suggestion be correct? Since a crystal with an applied-to-it ...
SFriendly's user avatar
  • 897
3 votes
1 answer
129 views

Can the electrical conductivity tensor of a crystal be obtained from a Hartree-Fock calculation?

Let’s assume that a crystal has been calculated by Hartree–Fock (HF) method (or DFT one), i.d., so to speak, the "first characteristics", which are eigenvalues and eigenvectors, as well as ...
SFriendly's user avatar
  • 897
6 votes
1 answer
229 views

Meaning of Kronecker Product in Transport Theory behind BoltzTrap2

I am somewhat confused by the use of a Kronecker Product in Madsen, Georg K. H. et al. “BoltzTraP2, a program for interpolating band structures and calculating semi-classical transport coefficients.” ...
Ian Bush's user avatar
  • 775
9 votes
1 answer
325 views

Transiesta output through a single gold atom

I am looking for the electron transport study in a single gold atom, like the system of single carbon atom shown in transiesta paper by Nick Papior et al. Computer Physics Communications, 212, 8-24, (...
sushil's user avatar
  • 329
6 votes
0 answers
94 views

Why do both my GGA+U and HSE06 calculations suggest that my material is a semiconductor, when I know it should be a conductor? [closed]

I am considering a material that exhibits metallic properties from the four probe measurements between 50-400K. Its electrical conductivity is about 15-20 S/cm and kept almost unchanged with ...
Binh Thien's user avatar
  • 2,095
8 votes
1 answer
332 views

Can deformation potential theory be applied to 2D and 1D systems?

I was pointed towards the use of the Deformation Potential (DP) theory to calculate the electron relaxation time in a previous question. However, I still have a doubt regarding its applicability to 2D ...
PBH's user avatar
  • 2,653
4 votes
0 answers
136 views

How to implement a Weyl semimetal in tight binding? [closed]

I want to study electronic and thermal transport properties of a Weyl semimetal. Until now, I have used only the continuum model hamiltonian ($H=k⋅σ$). As the continuum model has several limitations, ...
SG_commun20's user avatar
6 votes
2 answers
216 views

Are there tools to calculate the electrical conductivity of large (>1000 atom) nanostructures?

Are there any free to use tools which can be used to calculate the electrical conductivity of nanostructured materials. The systems that I am interested in consist of several thousand atoms, and ...
PBH's user avatar
  • 2,653
6 votes
0 answers
83 views

Validity of estimating electron relaxation time using the smallest cross section of a structure [closed]

I am studying nano-scale constrictions in semiconductor materials. Imagine two nano-particles joined together by a single point of crystalline contact to look like an hour-glass filled with sand. ...
PBH's user avatar
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