196
General Questions and Answers / Re: Negative inelastic transmission
« on: November 10, 2016, 11:52 »
It is impossible to say anything about this if you don't provide some details of the calculation such as a python script.
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197
General Questions and Answers / Re: Spectral energy density SED
« on: November 9, 2016, 00:21 »
SED method is not implemented in ATK at the moment. It can be computed using scripting, but we don't have any script at the moment that can do it.
198
General Questions and Answers / Re: color of spatial regions
« on: November 9, 2016, 00:15 »
At the moment it cannot be done. I would suggest you to export the image to povray format and add the spatial region with your desired color using povray.
http://docs.quantumwise.com/tutorials/povray/povray.html
http://docs.quantumwise.com/tutorials/povray/povray.html
199
General Questions and Answers / Re: Negative inelastic transmission
« on: November 8, 2016, 20:34 »
You should interpret it as an enhancement or suppression of the elastic transmission, the total transmission (elastic+inelastic) will be always positive.
200
General Questions and Answers / Re: ProjectionList
« on: November 7, 2016, 09:52 »
Hi Cyrille,
no unfortunately this cannot be done at the moment. Projections on angular momenta are on top of our priority list and will be available in ATK 2017.
Regards,
Daniele.
no unfortunately this cannot be done at the moment. Projections on angular momenta are on top of our priority list and will be available in ATK 2017.
Regards,
Daniele.
201
General Questions and Answers / Re: Projected local density of states
« on: November 7, 2016, 09:47 »
It cannot be done automatically, because the calculations of the electrodes and that of the central region are actually 3 differentet calculations.
However, the PLDOS includes the electrodes extensions. If your device is modeled correctly, then the PLDOS (that is, the electronic structure) at the left/right boundary of the PLDOS plot should be the same as that in the bulk electrodes.
However, the PLDOS includes the electrodes extensions. If your device is modeled correctly, then the PLDOS (that is, the electronic structure) at the left/right boundary of the PLDOS plot should be the same as that in the bulk electrodes.
202
General Questions and Answers / Re: boundary condition of nanotube within applied gate
« on: November 2, 2016, 16:41 »
Well, ATK calculations at finite biases are very well parallelized, so the actual solution is to run on more processes.
203
General Questions and Answers / Re: boundary condition of nanotube within applied gate
« on: November 2, 2016, 10:05 »
You should check if the Hartree difference potential is flat near the electrodes for that particular bias voltage (or for a slightly lower one). My guess is that you will find it is not flat, and this might be the reason for the poor convergence. It means that the central region is not sufficiently long to screen the electric field created by applying a bias voltage.
After checking that the electrostatic difference potential is OK, you can also try a less aggressive mixing (which will increase the number of steps needed to converge), such as
damping_factor=0.05,
number_of_history_steps=12,
max_steps=400,
After checking that the electrostatic difference potential is OK, you can also try a less aggressive mixing (which will increase the number of steps needed to converge), such as
damping_factor=0.05,
number_of_history_steps=12,
max_steps=400,
204
General Questions and Answers / Re: How to build phosphorene nanoribbons?
« on: October 31, 2016, 11:30 »
Hello,
You might first try to first build monolayer phosphorene as explained in this tutorial:
http://docs.quantumwise.com/tutorials/crystal_builder/crystal_builder.html
and then create a nanoribbon starting from the structure of monolayer phosphorene.
Regards,
Daniele.
You might first try to first build monolayer phosphorene as explained in this tutorial:
http://docs.quantumwise.com/tutorials/crystal_builder/crystal_builder.html
and then create a nanoribbon starting from the structure of monolayer phosphorene.
Regards,
Daniele.
205
General Questions and Answers / Re: boundary condition of nanotube within applied gate
« on: October 31, 2016, 11:27 »
Hello,
1. yes, it makes perfect sense. Just a note: because you have an interface in the central region, you will have a dipole at the interface. I would suggest that you check how the Hartree potential decays along C, and make sure that all the electrostatic effects due to the dipole are confined in the central region. Since you have Dirichlet b.c. along C you want the potential to be flat in the region close to the electrodes. Check the section "The screening region" in:
http://docs.quantumwise.com/tutorials/atk_transport_calculations/atk_transport_calculations.html
Since screening is rather poor in 2D materials, you might need to use a longer central region.
2. yes you are right, your transistor setup is essentially the same as that used in the tutorial:
http://docs.quantumwise.com/tutorials/graphene_nanoribbon_device/graphene_nanoribbon_device.html#graphene-nanoribbon-device
So you can calculate the device by following the same guidelines.
Regards,
Daniele.
1. yes, it makes perfect sense. Just a note: because you have an interface in the central region, you will have a dipole at the interface. I would suggest that you check how the Hartree potential decays along C, and make sure that all the electrostatic effects due to the dipole are confined in the central region. Since you have Dirichlet b.c. along C you want the potential to be flat in the region close to the electrodes. Check the section "The screening region" in:
http://docs.quantumwise.com/tutorials/atk_transport_calculations/atk_transport_calculations.html
Since screening is rather poor in 2D materials, you might need to use a longer central region.
2. yes you are right, your transistor setup is essentially the same as that used in the tutorial:
http://docs.quantumwise.com/tutorials/graphene_nanoribbon_device/graphene_nanoribbon_device.html#graphene-nanoribbon-device
So you can calculate the device by following the same guidelines.
Regards,
Daniele.
206
General Questions and Answers / Re: Problem with DOS calculation
« on: October 31, 2016, 11:12 »
Did you manage to visualize the band structure as Jess said? Does the problem persist?
207
General Questions and Answers / Re: magnetism or nonmagnetism for carbon nanotube?
« on: October 20, 2016, 12:10 »
I would say that that simply means that the CNT is non magnetic, as it should 
The difference you see is probably due to numerical accuracy, which has to be increased if you want to compare spin-polarized and non-spin polarized calculations.
The difference you see is probably due to numerical accuracy, which has to be increased if you want to compare spin-polarized and non-spin polarized calculations.
208
General Questions and Answers / Re: Nanotube workfunction
« on: October 20, 2016, 11:46 »
yes, it is OK, the nanotube length does not matter.
209
General Questions and Answers / Re: Nanotube workfunction
« on: October 19, 2016, 15:00 »
I guess one the general principles are the same as those for the calculation of the work function for slabs:
http://docs.quantumwise.com/tutorials/work_function_ag_100/work_function_ag_100.html?highlight=work%20function
with the periodic direction of the nanotube being either along A or B.
http://docs.quantumwise.com/tutorials/work_function_ag_100/work_function_ag_100.html?highlight=work%20function
with the periodic direction of the nanotube being either along A or B.
210
Scripts, Tutorials and Applications / Re: script for calculation of elastic constant and verious modulas
« on: October 19, 2016, 10:10 »
We have run your script using ATK 2015.1 without any issue. See attached log file. It is likely that the error you see is not related to ATK but to your machine, such as insufficient memory.