QuantumATK Forum
QuantumATK => General Questions and Answers => Topic started by: sunray55 on May 23, 2009, 10:10
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Hi, I meet two questions when setup the "method" in the nanolanguage-scripter of VNL,
Q1, in "basis set", there is a "charge" option. In manual, it is difined as the net charge of that atom when generatiing basis orbitals.
may I know what is the meaning of it? does it mean if we set charge=1, an electron will be added into the whole system. If not, can we calculate charged system in twoprobe system?
Q2, In "Brillouin zone integration", does it mean the k-points of ELECTRODES of twoprobe system? in other word, if we use 1D nanotube electrodes, setting (1, 1, 500); if we use 3D buld gold electrodes, setting (15,15,15)?
Many thanks
Sunray
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Yes that would be two good choices - however you would do equally fine with (1,1,100) or perhaps even (1,1,50) for the nanotube. It will save alot of calculation time, but the results will be as good as with (1,1,50).
For the gold electrode (15,15,15) requires a lot of calculation, and I would personally go with something like (10,10, 30) - It would speed up the TwoProbe path with more than a factor of 2 and should give the same results.
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Confusing as it may be, the "charge" in the basis set parameters has nothing to do with the charge of the atom. It's just a parameter used to generate the basis set. All atoms are assumed to be neutral in ATK, but charge transfer can (and will) occur in a two-probe system.