QuantumATK Forum
QuantumATK => General Questions and Answers => Topic started by: wot19920302 on May 23, 2016, 12:38
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Dear Quantumstaffs:
I got transmission spectrums for pristine MoS2 nanoribbon(fig1) and vacancy MoS2 nanoribbon(fig2), respectly. These two transmission spectrums, I think, look strange. Considering 1D structures, I set k-points for calculators attached to both structures 1*1*100, and k-points for transmission calculating 1*1. Do I get correct transmission spectrums? If not, what's wrong with me?
I'm looking for your reply
Best regards :)
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Why do you think it's wrong?
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Well....It's my first time to analyse transmission spectrum. I think the curve of fig2 undulates much from -0.7eV to -2.0eV and the fig1 is step-like. Is that reseaonable? :o
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Yes, it's reasonable (which doesn't mean I say your calculation is perfect, for that one would have to check a few other things).
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Dear Anders Blom：
Thanks for your kindness. In fact, I fear the effect of a bad optimized structure on transmission spectrum, how can I check if the transmission spectrum is perfect?
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There is no simple way to see that from the transmission, but obviously you can compute the forces on the atoms, and if these are large then the structure is not well optimized.
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When we optimize structures using ATK, we set max_force and max _stress in optimization term. Does it mean we don't calculate the force of atoms in strcuture again after optimizing the structure?
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Huh?
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Dear Anders Blom :
You said :" obviously you can compute the forces on the atoms, and if these are large then the structure is not well optimized." . So if we want to calculate transmssion spectrum after optimization(it means we have set max_torce in optimization term and forces on atoms in the structure satisfy the max_force), should I compute forces on atoms again? :o
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Eh, no... Computing the forces just tell you how large they are - but you know that from the optimization...
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Eh, no... Computing the forces just tell you how large they are - but you know that from the optimization...
So you mean that I don't need to calculate the forces on the atoms after optimizing the configuration...am I right?
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Right... Actually the forces are printed during the optimization.
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thank you, sir! ;D
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Dear Anders Blom
I want to study effects of defects in MoS2 nanoribbon on thermoelectric properties. I know I should calculate electron transmission spectrum to get conductance,seebeck coefficient,electrical thermal conductance and get phonon thermal conductance using phonon transmission spectrum. But when I get ZT as the function of E-Ef, I find that the transmission value of E-Ef corresponding to ZTmax close to Zero! I don't know whether it's reasonable, and I also can't analyse conductance in different defect systems (because it's too small). I hope you can help me
Best wishes
Here are my scripts: