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Messages - Petr Khomyakov

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1
You need a computer with more memory for this calculation.

2
Jobs can be submitted through the Job Manager in QuantumATK-2019.03. You may also use the Job Manager to generate a script for submitting jobs directly on a remote machine.

3
Questions and Answers / Re: spin transfer torque - reg.
« on: October 17, 2019, 22:54 »
Jobs can be submitted through the Job Manager in QuantumATK-2019.03. You may also use the Job Manager to generate a script for submitting jobs directly on a remote machine.

4
Hello everyone´╝î
        I had a problem when I calculated the transport properties. The transmission spectrum of the field effect transistor with or without a dielectric layer is different, but the parameters are the same.

But what is the actual problem? The transport properties should depend on the dielectric properties of the insulating spacer between the channel and gate electrode, because one gets different capacitance for the systems with different dielectric constants of the spacer. To understand physics of this, one could imagine a planar capacitor with a fixed bias applied to the capacitor planes for vacuum (epsilon=1) and some dielectric (epsilon <> 0). Using higher-epsilon dielectric increases the capacitance of the system, https://en.wikipedia.org/wiki/Capacitor, C ~ epsilon.

5
Accounting for inelastic scattering is computationally-expensive indeed.

7
Does VNL requires hardware acceleration from a GPU and NVIDIA driver installed? 

Yes, VNL does take advantage of hardware acceleration. You should first try to update your graphics card driver. Note that support for the 2017.12 and 2016.4 versions have already been terminated. Please consider upgrading to 2019.03-SP1, you may apply for a free trial license at https://www.synopsys.com/silicon/quantumatk.html.

8
It looks like there is no enough memory on the machine you are using for this calculation.

9
2016.4 version is not supported either. You may consider applying for a free trial version of QuantumATK 2019.03-SP1 at https://www.synopsys.com/silicon/quantumatk.html to see the significant development and improvement of QATK capabilities and features since 2016. 

10
Which version of QuantumATK are you using?

11
I made a graphene armchair nanoribbon, 8 atoms wide. I optimized it geometrically. After optimization I used bandstructure script on it and I did not get any bandstructure file after completion of simulation.

It would be helpful to see your script and related log file. You can attach it to your post.

12
Questions and Answers / Re: Becke Johnson
« on: September 30, 2019, 11:50 »
Take a look at Section on "Parameters for TB09-MGGA exchange-correlation" in the manual at https://docs.quantumatk.com/manual/Types/ExchangeCorrelation/ExchangeCorrelation.html.

13
Questions and Answers / Re: Berry curvature
« on: September 30, 2019, 11:46 »
You may compute Polarization and Born effective charges using the Berry phase if that is what you mean by computing Berry curvature, https://docs.quantumatk.com/manual/Types/Polarization/Polarization.html. In the GUI, there are two analysis objects that can be used to compute Polarization and Born effective charges.

14
Questions and Answers / Re: SCF converge issue in Optimization
« on: September 26, 2019, 10:03 »
- I would suggest first checking convergence of the total energy with respect to energy cutoff, k-point sampling in a systematic manner for a static configuration, i.e., without doing relaxation; you should aim at convergence of the total energy within 1-10 meV per atom.   

- You may also consider using a different pseudopotential, e.g., more modern one such as PseudoDojo.

- Another thing, you could try to enable Preconditioner in Iteration control in the Calculator. That might help improving SCF convergence for slab/surface/2D material PW calculations.

15
Questions and Answers / Re: spin transfer torque - reg.
« on: September 25, 2019, 09:28 »
Deciding on k-point sampling is always a matter of convergence with respect to the k-point density. One should look at different samplings to see if the results (physical quantities of study)  obtained converge within some tolerance~accuracy. In that sense, nobody can tell you for sure that certain k-grid is OK for your particular system of study. You should perform convergence tests - this is a routine procedure for any kind calculations where one should converge results with respect to computational settings.

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