Messages

1

Plugin Development / QATK 2024-09 IV Curve

« on: February 12, 2025, 13:40 »

Hello everyone,

I previously used the QATK 2022-03 version and have performed current bias voltage calculations. Nowadays, I use the newest version of QATK 2024-09, however, the IVCurve analyzer is absent. Do we need to calculate with the script or can the IV Characteristic study object do this calculation (only current-bias voltage calculation without gate voltage) ? Also, when I obtain the current-bias voltage values via scripting, I cannot plot the result file i.e. IVCurve.hdf5 file as before.

I would be glad if you can help.

2

General Questions and Answers / e-ph coupling

« on: December 10, 2024, 06:57 »

Dear experts,

I do not fully understand the connection between initial state energy range and energy tolerance in e-ph coupling calculations. How do we choose energy tolerance set to 0.01 (eV) and the Initial state energy range to go from -0.5 to 0.5 in phonon-limited mobility in graphene using the Boltzmann transport equation tutorial. If we set energy tolerance to 0.1 or 1 eV what happens?

For example, if the phonon energy is 0.02 eV and the energy tolerance is set to 0.01 eV, the difference between the initial and final electronic states should be within 0.01 eV of 0.02 eV (i.e., between 0.01 eV and 0.03 eV) for the electron-phonon matrix element to be calculated. Is it true?

3

General Questions and Answers / Re: Electrode and electrode extension size

« on: July 12, 2023, 11:35 »

Hello again Dr.Blom,

I try to understand how length of the electrodes affects the IV curve of the our device model. Therefore I have made some tests.

I have noticed that, when I increase the electrode extension length, minimal electrode length is also increased to be the same as the electrode extension length. However if I have first increased the size of the central region at the interface of the respective electrode, and secondly I have increased the electrode extension length, minimal electrode length remains same. What is the origin of this difference and which geometry makes sense?

I look forward to hearing from you.

4

General Questions and Answers / Re: Hamiltonian Derivatives

« on: June 20, 2023, 11:24 »

Hello again,
Hamiltonian derivatives calculation has been completed by increasing atomic displacement from 0.01 Ang to 0.1 Ang. I know that Hamiltonian derivatives is calculated via finite difference method, so increasing the default value of atomic displacement gives the wrong result?

5

General Questions and Answers / Re: Electrode and electrode extension size

« on: June 13, 2023, 10:51 »

Thank you Dr. Blom, I got it.

6

General Questions and Answers / Electrode and electrode extension size

« on: June 9, 2023, 12:13 »

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?

7

General Questions and Answers / Re: Hamiltonian Derivatives

« on: May 17, 2023, 15:10 »

Can you suggest any recipe to overcome this problem?

8

General Questions and Answers / Re: Hamiltonian Derivatives

« on: May 6, 2023, 13:25 »

Actually the main problem arises when qatk performing the Fermi level calculation. This first task, unfortunately is not over. You can find the log files at the attachmenet.

9

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?

10

General Questions and Answers / Re: ExternalPotential

« on: April 14, 2023, 10:36 »

Dr. Blom, sorry to take your time, I think I phrased it wrong. What I mean is that when we dope electrodes, compensation charges are automatically added to the both electrodes and the central region, with the same amount and type of doping by the algorithm. We shouldn't change these compensation charges, right?

11

General Questions and Answers / Re: ExternalPotential

« on: April 10, 2023, 12:37 »

Thank you Dr. Blom. As far as I understand, we should not change the charge added by the algorithm to left/right eletrode as well as central region to compensate for the doping. Am I right?

12

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])

13

General Questions and Answers / Re: Oscillations in EDP

« on: February 1, 2023, 16:19 »

Thank you Dr.Blom.

14

Scripts, Tutorials and Applications / Re: Zn-ZnO-Zn Transport Calculation

« on: February 1, 2023, 16:18 »

Thank you for your comments. I will go back to tutorial and make the calculations again under the guidance of your advice.

15

General Questions and Answers / Re: Oscillations in EDP

« on: January 18, 2023, 13:00 »

Any comment?