27
votes
Accepted
Given that Kohn-Sham DFT is strictly a ground-state method (at 0 K), how is it sufficient to describe materials in real-life applications?
These are a few extra points to complement Andrew Rosen's comprehensive response:
To be absolutely clear, typical DFT calculations are not performed at 0K, a better description of what happens is ...
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22
votes
Given that Kohn-Sham DFT is strictly a ground-state method (at 0 K), how is it sufficient to describe materials in real-life applications?
You are correct that KS-DFT, strictly speaking, involves calculations of a potential energy surface at 0 K. However, if you accept that the density functional approximation you are using is ...
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12
votes
Given that Kohn-Sham DFT is strictly a ground-state method (at 0 K), how is it sufficient to describe materials in real-life applications?
Kohn-Sham DFT may only be rigorous at zero temperature, but at nonzero temperature,
Kohn-Sham-Mermin DFT is an equally rigorous replacement. There are two major differences
Rather than deriving the ...
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9
votes
Why is the Nonequilibrium Green’s function (NEGF) method for quantum transport not implemented in plane wave codes like VASP and Quantum Espresso?
I quote from Derek Stewart that gave the answer here:
Since VASP relies on a non-localized basis set (plane waves), it is not possible to implement a non-equilibrium Green's function approach ...
9
votes
Accepted
About the surface Greens function method for calculating the surface state
The surface Green's function method is described in detail here, but here is a summary.
Principal Layers: Block Tridiagonal Form
We consider a semi-infinite system (a surface with an infinite bulk ...
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6
votes
About the surface Greens function method for calculating the surface state
You can see the open-source package WannierTools:
https://github.com/quanshengwu/wannier_tools
A brief description:
We present an open-source software package WannierTools, a software for the ...
- 14.9k
4
votes
Accepted
Approximation of Dyson's Equation
I think the justification is just that this is the simplest approach, since $E$ is a scalar and $\boldsymbol{\epsilon}$ is a vector. If you only take the diagonal part of $\Sigma$, you see that the ...
- 17.9k
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
2
votes
Accepted
Implemetation of NEGF in TranSIESTA
Self-energies are calculated from a pristine, bulk calculation of only the electrode.
This is a requirement of the self-energy algorithm. This also forces the boundary conditions of the electrodes.
...
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1
vote
How can I get the projected density of states within the Green's function method?
I'm not sure I fully understand the question here. The local density of states is as you defined (see equation 10 of
https://arxiv.org/pdf/1907.11302.pdf too)
Could you define what you mean by ...
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