16
General Questions and Answers / Local bandstrcture
« on: February 20, 2017, 14:47 »
Hi in the screenshot, what does sigma stand for?
Is it standard error? SD ?
Is it standard error? SD ?
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17
General Questions and Answers / ATK Sabalcore no of nodes
« on: February 17, 2017, 18:45 »
Dear Sir,
What is the maximum available number of nodes and cores per node for running ATK on demand on Sabalcore?
I saw the tutorial
http://docs.quantumwise.com/guides/atk_on_demand/atk_on_demand_sabalcore.html
where it's said:
You can see the list of available nodes and corresponding details by logging ini via SSH to Sabalcore and use the command upnodes
but how to login to sbalcore via ssh ?
What is the maximum available number of nodes and cores per node for running ATK on demand on Sabalcore?
I saw the tutorial
http://docs.quantumwise.com/guides/atk_on_demand/atk_on_demand_sabalcore.html
where it's said:
You can see the list of available nodes and corresponding details by logging ini via SSH to Sabalcore and use the command upnodes
but how to login to sbalcore via ssh ?
18
General Questions and Answers / Total energy and energy cut-off
« on: February 14, 2017, 15:51 »
Is there any correlation between total energy of a system and the energy cutoff used in the simulations. Say I want to calculate the total energy of a large (50-60 atoms) supercell would there be any difference if I use a cutoff of 300eV in one case and 600eV in other for my LDA-PZ calculations?
19
General Questions and Answers / Edit nc files
« on: February 13, 2017, 13:34 »
I have a .nc file with a lot of objects in it. Many of which I do not need anymore. To stop bloating the file size and to keep only relevant gIDs what should be done?
Is there any way to selectively remove/delete certain objects from a .nc file?
Is there any way to selectively remove/delete certain objects from a .nc file?
20
General Questions and Answers / Bandstructure export data
« on: February 13, 2017, 12:10 »
In the ATK 2016.3 , the export bandstructure has lot more data including the k-point co-ordinates which is very good, but I want to export a more simple two column data (like earlier versions of ATK did) to a .dat file from the bandstructure object.
Could you help me with a python script for that?
Could you help me with a python script for that?
21
General Questions and Answers / Eff mass fitting plots
« on: February 11, 2017, 10:26 »
Hi,
To get the effective mass fitting plots in ATK 2016.3 I am trying the Local Bandstructure as in
http://docs.quantumwise.com/tutorials/inas_2d_mgga/inas_2d_mgga.html
But how to fit the top of the band in a symmetric way (i mean the two arms of the parabola/ fitting curve)?
What I see is just half of the parabola. This is true for points intermediate between G and Z also.
To get the effective mass fitting plots in ATK 2016.3 I am trying the Local Bandstructure as in
http://docs.quantumwise.com/tutorials/inas_2d_mgga/inas_2d_mgga.html
But how to fit the top of the band in a symmetric way (i mean the two arms of the parabola/ fitting curve)?
What I see is just half of the parabola. This is true for points intermediate between G and Z also.
22
General Questions and Answers / T(E) or Ge(E)
« on: February 10, 2017, 21:13 »
In the manual
http://docs.quantumwise.com/manuals/Types/TransmissionSpectrum/TransmissionSpectrum.html
mentions A fully transmitting channel contributes 1 per spin. If you sum the spin channels, the total transmission of an ideal system is 2. Often, it is the energy dependent conductance which is reported in articles
Ge(E)=(e^2/h)T(E)
If total transmission of an ideal system is 2, what does quantumwise actually plot for the transmission spectra T(e) or Ge(E) ?
Because in many cases the value of transmission is well in excess of 2.
http://docs.quantumwise.com/manuals/Types/TransmissionSpectrum/TransmissionSpectrum.html
mentions A fully transmitting channel contributes 1 per spin. If you sum the spin channels, the total transmission of an ideal system is 2. Often, it is the energy dependent conductance which is reported in articles
Ge(E)=(e^2/h)T(E)
If total transmission of an ideal system is 2, what does quantumwise actually plot for the transmission spectra T(e) or Ge(E) ?
Because in many cases the value of transmission is well in excess of 2.
23
General Questions and Answers / Green's function method T(E)
« on: February 10, 2017, 20:44 »
Hi,
I was wondering when we calculate the transmission spectra of a material is it with the "non-equilibrium" Green's function method? Beacuse at zero bias the system is still in equilibrium.
Should it be just
"equilibrium transmission was evaluated with Green's function method" or
"transmission was calculated with DFT"
Because T(E) seems a fundamental quantity which helps in calculating current etc. by Landauer method.
I was wondering when we calculate the transmission spectra of a material is it with the "non-equilibrium" Green's function method? Beacuse at zero bias the system is still in equilibrium.
Should it be just
"equilibrium transmission was evaluated with Green's function method" or
"transmission was calculated with DFT"
Because T(E) seems a fundamental quantity which helps in calculating current etc. by Landauer method.
24
General Questions and Answers / Export data format
« on: January 11, 2017, 15:37 »
Export of transmission data is giving out put in the following format
...
-2.000000e+00 6.999983e+00
-1.980000e+00 6.999996e+00
-1.960000e+00 6.999998e+00
...
while I need the data in this format (below)
...
2.0106192983e+12 1.9142005976e+00
2.0734511514e+12 1.9023768591e+00
2.1362830044e+12 2.2092658409e+00
...
How to get this?
...
-2.000000e+00 6.999983e+00
-1.980000e+00 6.999996e+00
-1.960000e+00 6.999998e+00
...
while I need the data in this format (below)
...
2.0106192983e+12 1.9142005976e+00
2.0734511514e+12 1.9023768591e+00
2.1362830044e+12 2.2092658409e+00
...
How to get this?
25
General Questions and Answers / Device supercell heterojunction
« on: January 4, 2017, 23:01 »
If we have a heterojunction device supercell (i.e. two different materials A aand B junction at the middle of the central "Device region") as in http://quantumwise.com/support/tutorials/item/94-carbon-nanotube-junctions
and make a device from Bulk config/ molecular config, what determines whether the electrodes will be considered as periodic? (i.e. is it necessary to have the length of the electrode region to be physically much longer than the central region or vice versa to assume ideal contacts)
Before making the device (i.e. the bulk config) if we repeat the structure in C it becomes A-B-A-B-A-B, what ensures that when we make a device configuration, that it is actually a A-B heterojunction we are simulating.
I just want to know how ATK handles this internally and makes the choice?
and make a device from Bulk config/ molecular config, what determines whether the electrodes will be considered as periodic? (i.e. is it necessary to have the length of the electrode region to be physically much longer than the central region or vice versa to assume ideal contacts)
Before making the device (i.e. the bulk config) if we repeat the structure in C it becomes A-B-A-B-A-B, what ensures that when we make a device configuration, that it is actually a A-B heterojunction we are simulating.
I just want to know how ATK handles this internally and makes the choice?
26
General Questions and Answers / Peltier coefficient
« on: January 4, 2017, 22:50 »
In the tutorial https://quantumwise.com/documents/tutorials/latest/Phonon/index.html/chap.thermoelectric.html
It's mentioned "For an undoped nanoribbon, the Fermi level is in the middle of the band gap. To get a significant Peltier coefficient, the Fermi level must be at a band edge, corresponding to a doped nanoribbon. The plugin allows for shifting the Fermi level, and Figure 7 shows the result for \Delta E_F = 0.08 eV, corresponding to an n-doped nanoribbon. "
What happens if it is a metallic nanoribbon? Do we still need doping for getting significant Peltier coeff. even though there are states at Ef=0 ?
It's mentioned "For an undoped nanoribbon, the Fermi level is in the middle of the band gap. To get a significant Peltier coefficient, the Fermi level must be at a band edge, corresponding to a doped nanoribbon. The plugin allows for shifting the Fermi level, and Figure 7 shows the result for \Delta E_F = 0.08 eV, corresponding to an n-doped nanoribbon. "
What happens if it is a metallic nanoribbon? Do we still need doping for getting significant Peltier coeff. even though there are states at Ef=0 ?
27
General Questions and Answers / ATK Classical
« on: December 21, 2016, 13:57 »
In the recent versions of QuantumWise it is not possible to do electronic bandstructure calculations with ATK Classical anymore. However in the earlier releases it was very much possible to do so. Why has the functionality been turned off and is there a workaround.
It can be accuracy issue I understand but say just for testing different classical potentials if I do need some results it is no longer possible to have them.
Is it possible to work around the GUI with scripting.
It can be accuracy issue I understand but say just for testing different classical potentials if I do need some results it is no longer possible to have them.
Is it possible to work around the GUI with scripting.
28
General Questions and Answers / FHI-aims input file with VNL
« on: December 9, 2016, 17:45 »
How can we build input files for FHI-aims with VNL. I have FHI installed separately (not part of ATK package) on a different system. Is it possible to do something similar to the VASP scripter? I can make FHI input files with VNL then. Would be very helpful.
29
General Questions and Answers / Export data Bandstructure -problem
« on: December 6, 2016, 20:05 »
I want to export data in *.dat format and only need the two columns. I am always getting *.txt files and 4 columns. VNL 2015 used to work fine if I exported from the 2D plot bandstructure. The BS 2D plot is also missing in 2016. Please correct this so I can export 2 columns in .dat.
I tried renaming the files but then the columns are not properly recognized in plotting software as Origin.
I tried renaming the files but then the columns are not properly recognized in plotting software as Origin.
30
Installation and License Questions / Installation Problem 2016.3
« on: November 16, 2016, 11:56 »
Windows 10 showing smart screen filter alert, regarding the installer as unsafe. Please correct this.