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Topics - gozde

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Hi all,

My results obtained from transport calculations vary with electrode size. The results I obtained when the minimum electrode size is one unit cell i.e. 3.7 ang and the electron extension is two unit cells i.e. 7.4 ang (QATK default) are quite different from when the minimum electrode size is two unit cells i.e. 7.4 ang and the electrode extension size is two units cells, i.e. 7.4 ang. I wonder, which parameter do we need to change in order to obtain accurate results? Is it the electrode size or the electrode extension size?

2
General Questions and Answers / Hamiltonian Derivatives
« on: April 14, 2023, 10:59 »
Hello,
I succeed to obtain hamiltonian derivatives for structures which have unitcell composed of 2, 3 and 4 atoms. However, executation tasks do not progress even one step in unitcell containing 24 atoms. I heva used thight parameters to obtain phonon dispersion accurately and I achieved. I guess this problem can be originated from high accuracy of the parameters of the LCAO calculator because I use, analysis from file (optimized bulk structure) before the study objects. Unfortunately executation task stays on the same step 1/73 for hours and does not progress.
Do you have any suggestion to make progress?

3
General Questions and Answers / ExternalPotential
« on: April 3, 2023, 23:29 »
Hi All,

When we dope only the electrodes, why is the same type and amount of compensation charge has added to electrodes and central region as an external potential? Is this necessary to neutralize the system? The second question is, If we want to dope the electrodes with the same type and amount of charge and remain the central region undoped, should this part of the script be as follows?  And the last question, if we change the type or amount of the compensation charge manually which is added to central region as an external potential, how the results are affected, i.e. IVCurve?

I'm looking forward to your reply.

Code
# Add external potential
external_potential = AtomicCompensationCharge([
    ('doping_0', 0.01),
    ('doping_1', 0.01)
    ])

left_electrode.setExternalPotential(external_potential)

# Add external potential
external_potential = AtomicCompensationCharge([
    ('doping_0', 0.01),
    ('doping_1', 0.01)
    ])

right_electrode.setExternalPotential(external_potential)

# Add external potential
external_potential = AtomicCompensationCharge([
    ('doping_0', 0.01),
    ('doping_1', 0.01)
    ])

central_region.setExternalPotential(external_potential)

# Add tags
device_configuration.addTags('doping_0', [ 0,  1,  2,  3,  4,  5,  6,  7,  8,  9, 10, 11, 12,
                                          13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23])
device_configuration.addTags('doping_1', [48, 49, 50, 51, 52, 53, 54, 55, 56, 57, 58, 59, 60,
                                          61, 62, 63, 64, 65, 66, 67, 68, 69, 70, 71])

4
General Questions and Answers / Oscillations in EDP
« on: December 8, 2022, 09:55 »
Hi everyone,

I have studied on 5 nm 2D pn junction (doped with 0.005 e/atom) and I have obtained EDP as in figure. What can be the origin of these oscillations? Could these oscillations be due to short length of device size or low doping amount? In addition, EDP should become flat close to the electrodes, right?

Best regards.

5
General Questions and Answers / About Building an Interface
« on: November 8, 2022, 14:00 »
Dear experts,

How can we determine the number of layers to include when creating an interface between metal and semiconductor? For example there are different number of layers are added at the last step in Ag(100) and Au(111) and Ag-Si tutorials.

Best regards.

6
General Questions and Answers / Doping pn junction
« on: October 26, 2022, 18:27 »
Hi all,
I have a question about "add doping script".

Do we need to use the doping script which is mentioned in the "silicon junction tutorial" to dope the any device configuration or should we only use the doping tool instead of tag tool?
Also is there any difference between following "by expression --> selection tools --> tags" and "doping tool"?

I will appreciate your answers.

7
General Questions and Answers / Graphene Mobility
« on: September 27, 2022, 09:01 »
Hi all,

I studied on "Phonon-limited mobility in graphene using the BTE" tutorial. Unfortunately, I have found different mobility results for graphene. I have attached e-ph and mobility script as well as results file. Where could I go wrong?
I will be glad if you can help.

8
Hello,

I have a question about Zn-ZnO-Zn junction tutorial. I tried to create the geometry by following this link "https://forum.quantumatk.com/index.php?topic=5320.msg22991#msg22991", however I can not understand how we select the smallest possible number of atoms, repeat a bit on both sides of the interface.

Also should we make any transformation when retrieving the Zn and ZnO geometries since the first one is hexagonal and the latter is face centered cubic?

Thanks.

9
Hi all,

I am a new user of ATK. I have made a tutorial of calculating the transmission spectrum of graphene and MoS2. Now I try to calculate transmission spectrum of 2D perfect sheet of InSe, however I can not use ATK-SE. It is written that " Internally invalid: The basis set is incompatible with the configuration." My question is, what calculator can be used for obtaining transmission spectrum of InSe or GaSe?

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