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QuantumATK => General Questions and Answers => Topic started by: hzkvictory on July 16, 2012, 05:24

Title: conductance-gatevoltage results are in contradict with the experiment ?
Post by: hzkvictory on July 16, 2012, 05:24

Graphene was widely studied both on theory and experiments. Most basic experiment properties have been tested by simulations.
   I noticed that conductance-gate voltage is very common in experiments, but little simulation by ATK is researched. So I do a lot of work on it.
   However, the result are in contradict with the experiment results.

In experiments, resistance--gate voltage have almost the same trend as following(http://www.sciencedirect.com/science/article/pii/S0038109808001178)
I did three series of calculations, bulk graphene, armchair-edged graphene, zigzag-edged graphene.

 bulk graphene
attached is the related documents:first,conductance--gatevoltage[-1.0,1.0V]every0.1Va point.
                                                    second,transmission spectrum under all gate voltage.(interesting to find the gate voltage do not affect bulk graphene)
                                                     third,script to calculate the transmission
                                                     forth,gatescan script

Title: Re: conductance-gatevoltage results are in contradict with the experiment ?
Post by: Nordland on July 16, 2012, 22:35

Your link with the experiments is not working?

Title: Re: conductance-gatevoltage results are in contradict with the experiment ?
Post by: Nordland on July 17, 2012, 12:07

I just quickly put together a calculation of the same, because your approach of the system setup will not give any good results,
as it contains a set of flaws.

This is how I would setup the structure, and this is my conductance as a function of gate voltage.

Title: Re: conductance-gatevoltage results are in contradict with the experiment ?
Post by: hzkvictory on July 19, 2012, 11:22

Thank you,sir.
 [1]At first I re-calculate your script and get the same plot.
 [2]Then I compare mine setup with yours , finding two big differences:1.In A direction, your boundary condition is [Dirichlet, Neumann], while mine is [Neumann, Neumann]
                                                                                                       2.you get the plot by      append( transmission_spectrum.conductance().inUnitsOf(Siemens) * 1e6 ),    which I don't understand.  while, I get the plot by Analyzer>Analyzers>Conductance>Drop NC files.
 [3]Attached is my script with your setup, and Analyzer--produced plot, the plot have different unit. Please tell where i am wrong in ploting.
 [4]Here is the experiments results  http://quantumwise.com/forum/index.php?topic=1713.0
      As is shown, your calculation is still in contradict with the experiments. This needs more discussion and hope to get more attention.