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Topics - kaypu

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46
Dear everyone:
              i have a question about transmission spectrum. In my opinion, a transmission channel has a maximum quantum conductance G0, Consider a channel with two spin-degenerate levels, the maximum quantum conductance is 2G0,

in my two probe system, i calculate the transmission spectrum from -2eV to 2eV,

the question is :

the transmission coefficient from -1.5eV to 1eV is larger than 2, is it right?


47
Dear everyone
    i want to study the transport properties in molecular devices with different orientation, When the  molecule is contacted by two Au (111) electrodes in different orientation, the Fermi energy of isolated molecule can be set to the electrochemical potential of the electrode. In the process, our calculation indicates that there is a tiny charge transfer between the gold electrode and the molecules. For one orientation, the charge transfer is 0.22e, for another is 0.07e. The Fermi energy of the isolated molecule in different orientation is the same. why the charge transfer is different in the process of alignment?

48
when i put the molecule into the electrode, how to confirm the distance between the molecule and the electrode?
if i want to  optimize the distance between the surface layer and the molecule

thank you
 

49
General Questions and Answers / qusetions on temperature
« on: December 11, 2010, 10:40 »
i calculate the two probe system, in the low bias voltage area,between -0.8V to 0.8V, it is convergence,and i use the temperature 300k.
but from -0.9V to 1.5V, it isn't convergence, so i increase the temperature to 1000k, it converges. will this affact the results much? i mean the transmission spectrum,I-V, conductance.
thank you

50
General Questions and Answers / question on convergence
« on: December 11, 2010, 10:29 »
hello everyone
   the distance between the molecular and the electrode will infect the convergence ,is it right??
   if the distance is too short, it is hard to converge???

51
i'm a rookie
canyou tell me the diffenence between the transmission spectrum and transmission coefficients
i think the transmission coefficients is calculated in a fixed energy (such as E=0),but the transmission spectrum is calculated in a energy range(such as -2ev to 2ev),if i choose the energy range from 0ev to 0ev. at this time, are they equal to each other??
 thank you

52
General Questions and Answers / questions about the convergence
« on: December 7, 2010, 17:56 »
Dear blom:
     i've some questions about the convergence
① in my two probe system,when the bias voltage is set at -0.9V, it doesn't converge at all,  but in 0.9V it works well. why? because of the asymmetry of the molecular or the position of the molecular in the two probe?              
② i increase the temperature of the electrode from 300k to 1000k in the -0.9V,but it doesn't work!! what should i do ?
 the electrode iteration mixing parameters are set as follows:
     iterationMixingParameters
    algorithm = IterationMixing.Pulay,
    diagonal_mixing_parameter = 0.01,
    quantity = IterationMixing.Hamiltonian,
    history_steps = 15
and the k point is 5*5*100,

Pages: 1 2 3 [4]