Messages

1

General Questions and Answers / Re: Editing Transmission Plot

« on: January 7, 2021, 17:26 »

Thank you 

2

General Questions and Answers / Editing Transmission Plot

« on: January 7, 2021, 13:15 »

Hello,
Is there a simple way for me to make T(E) the Y axis and E(eV) the X axis for Transmission spectra in Quantum ATK?
I have found plenty information in editing plots in Quantum ATK, however none seem to apply to transmission spectra plots.
Is there any way I can swap the X and Y values on the Transmission plots or do I have to extract the data and plot it myself?
Kind regards,

Paul

3

General Questions and Answers / Modelling charged molecules in molecular junctions

« on: April 21, 2020, 10:59 »

Hello,

I was hoping you could help clarify something. I'm currently doing transport studies on a series of molecular junctions (Image attached for reference). The molecule in question(POM) is easily reduced and so I am trying to compare the transport of the -3 through -9 redox states of the molecule.  To do so, I optimise the molecule (with DFT)  with different charges. I then build the device with the optimised molecule. I assumed that as the optimisation has taken into account the charge, and the number of electrons ( checked by MES) is consistent ( increases by 1 as charge increases), when placed between electrodes, although you can't specify the charge of the molecule in the device, the number of electrons (in the molecule) should be consistent with its redox state.

However, when I calculate the MES(focusing only on the molecule) for the different devices the number of electrons is consistently 628 ( which is the number for the -4 state). The transmission spectra, HOMO-LUMO gap are all different for all devices, suggesting that the same molecule is not being modelled. But I want to be sure that the charge of the molecule is being modelled correctly and that it is a result of it reaching equilibrium with the electrodes or something else physical rather than an error in the modelling of the device.

If this is erroneous, is there a way I can specify the charge of the molecule within the device?

4

General Questions and Answers / Modelling Point Charges

« on: January 13, 2020, 15:07 »

Hello,

I am hoping someone could help. I am trying to model the effect countercations have on a molecule. The countercations in the real system are tetrapropylammonium cations, but due to its size/computational cost, I want to model the countercations as a point charge, is there away to do this?

Thanks

5

General Questions and Answers / SlaterKoster Parameters for Tungsten

« on: October 31, 2019, 12:57 »

Hello,

I was hoping somebody could help.
 I am currently attempting to do transport calculations on a molecule that contains Tungsten, due to the size of the system I wanted to attempt DFTB/ Slater-Koster to gain some computational speed. However there doesn't seem to be any SlaterKosterTables for Tungsten. Does anyone have any suggestions on how I can use this method on Tungsten containing system?

Is there anyway to fit parameters from previous DFT Geometry Optimisation calculations on the Molecule?

Thanks in Advance