QuantumATK Forum
QuantumATK => General Questions and Answers => Topic started by: jjhskang on April 9, 2011, 04:05
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Hi!
I am making two probe calculations using atk2008.10.
In one of them, I find that the SCF calculation at zero bias gives
q = 412.42189 e Etot = -2064.51856 ...... at the end of the convergence iteration.
However, the total # of electrons in the scattering region should be 413, and some electrons disappeared.
What is the problem here and how can I solve this problem?
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(1) Is it because I have not included all the poles in the calculation?
I used the default value of integral_lower_bound, i.e., 3eV.
(2) I believe that I have inlcuded farely large number of atoms in the scattering region in order to ensure completel screening in the scattering.
Hi!
I am making two probe calculations using atk2008.10.
In one of them, I find that the SCF calculation at zero bias gives
q = 412.42189 e Etot = -2064.51856 ...... at the end of the convergence iteration.
However, the total # of electrons in the scattering region should be 413, and some electrons disappeared.
What is the problem here and how can I solve this problem?
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The two-probe calculation in ATK is carried out under open boundary conditions. That means, that charge is not conserved in the central region, and this allows for finite-bias non-equilibrium calculations.
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the lost of the charge can be considered as the alignment of the Fermi energy,
alignment means the Fermi energy of the electrode and the scattering area, is that right?
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Basically, yes.
Do note however that since the electron distribution in the central region by definition is not in equilibrium, there is not, strictly speaking, any well-defined Fermi level in this region. It's position-dependent, to lowest order perhaps similar to a linear ramp between the applied biases, but formally it cannot be defined.