Questions tagged [transport]

Questions related to transport phenomena (e.g. charge transfer, heat conduction, molecular diffusion).

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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
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
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
  • 569
2 votes
1 answer
147 views

Gate potential wiith siesta/transiesta

I want to study the effect of adding a gate to quantum transport device, the problem that i encounter is that in siesta manual there are two methods to do so, the first is "Geometry.Charge" ...
Mohamed Amine's user avatar
7 votes
0 answers
136 views

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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3 votes
1 answer
86 views

Error in TranSIESTA: "The electrode down-folding region is 0 in the device region"

When I run a tranSIESTA calculation, the SCF converges, and the TBtrans output shows the following error: ...
Hananab'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
  • 41
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
3 votes
0 answers
125 views

Transiesta SCF not converged [duplicate]

I have encountered a convergence problem in my structure device in Transiesta calculation, the calculation doesn't converge. Recently I try to decrease the mixing weight parameter to 0.00001. For some ...
Hananab's user avatar
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4 votes
0 answers
158 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
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6 votes
1 answer
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TBtrans/Transiesta, error: "connectivity is not perfect"

I have a problem with a Transiesta calculation, I could not get the transmission (TBT calculation) as well DOS and current. I perform the I-V for graphene nanoribbons (electrode containing 20 atom , ...
Hananab's user avatar
  • 369
14 votes
1 answer
260 views

What are differences between Mott and Anderson transitions?

Can anyone please explain the differences between Anderson and Mott insulator-metal transition? I found some information in the book named "The_Physics_of_Amorphous_Solids".
Binh Thien's user avatar
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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
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6 votes
0 answers
69 views

Value of density of state effective mass and transport effective mass to calculate conductivity [closed]

How can density of state effective mass and transport effective mass can be defined to calculate conductivity for a cubic system with parabolic but anisotropic dispersion relation? What will be the ...
Shalini's user avatar
  • 1,605
9 votes
1 answer
296 views

Which energy should I consider while trying to analyse the variation in transport coefficients with temperature?

I am using the BolzTraP code [I'm completely new to this code] to calculate the thermo-electric coefficients as per this tutorial. And the output file obtained from BoltzTraP is given below. The ...
Anoop A Nair's user avatar
  • 4,476
10 votes
4 answers
819 views

Tools for electronic transport calculations

Electronic transport calculations play an important role in device simulation. What tools can do electronic transport calculation? I am familiar with TranSIESTA (a module of SIESTA program) and ...
Camps's user avatar
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9 votes
1 answer
1k views

How is SIESTA and TranSIESTA different from plane wave DFT codes?

This question is complementary to a previous question. I have experience with the plane-wave DFT codes VASP and Quantum ESPRESSO. I would like to try SIESTA for the main purpose of using TranSIESTA ...
Thomas's user avatar
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6 votes
1 answer
148 views

Conductivity Computations of Molecular Wires [closed]

I am interested to compute the conductivity properties of some molecular organic wires in SIESTA. Since I am new in SIESTA, I would appreciate a guide for beginners to this field.
Aggelos Avramopoulos's user avatar
14 votes
3 answers
599 views

Is there a (free) GUI to setup transport calculations using SIESTA?

I am very interested in doing transport calculation with SIESTA. My problem is that it is a little hard for me to understand and setup the input files to be used with TranSIESTA (the module that do ...
Camps's user avatar
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17 votes
2 answers
225 views

How to simulate atomic scattering from solid walls at finite temperature for a particles in a box simulation?

I'm not sure if this will be considered on-topic, let's see what happens. I've asked this previously in Physics SE and it was closed as needing focus. It is now past 30 days and too late to consider ...
uhoh's user avatar
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