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Messages - Jahanzaib

Pages: [1] 2 3 ... 7
1
General Questions and Answers / Re: Band Structure
« on: Yesterday at 01:41 »
Hello Expert
Is there a way to change the colors for spin up and down bands in the given figure below? I have checked and tried and I haven't find anything to change color. Please see the attached pictures.

Im previous discussion, I was interested to extract BS using python code?

2
General Questions and Answers / Re: Band Structure
« on: November 1, 2024, 04:12 »
Actually I saw your code in the previous discussion where you mentioned to extract BS using python code. The code is given below:
So, I am interested for my sytem, but it doesnot given what I saw in GUI. I already knew how to combine both BS and DOS in GUI, but i think using python code, both looks more better for publication ;D ;D

from NanoLanguage import *

# -----------------------------------------------
# Parameters
# -----------------------------------------------
max_band = 100
min_band = 0
min_energy = -20
max_energy = 10
show_grid = True
title = 'Gold FCC'

# Read the bandstructure from a file.
bs = nlread('bandstructure.nc', Bandstructure)[0]

# Read the data in.
data = bs.evaluate()

# Setup the axises.
axixes = bs._axisGUI()
ticks = bs._ticksGUI()
loc = [ t[0] for t in ticks]
label = [ t[1] for t in ticks]
for i in range(len(label)):
    if len(label) != 1:
        label = r'$\Gamma$'

# Slice the data.
sliced_data = data[:,min_band:max_band]

import pylab
pylab.figure()
pylab.plot(axixes, sliced_data, 'k-')
pylab.plot(axixes, numpy.array(axixes)*0.0, 'k--')
pylab.xlabel('K')
pylab.ylabel(r'$\epsilon_i$ / eV')
pylab.xticks( loc, label)
pylab.ylim(min_energy, max_energy)
pylab.grid(show_grid)
pylab.title(title)
pylab.show()


3
General Questions and Answers / Re: Band Structure
« on: October 31, 2024, 00:53 »
Thank you so much. Is there a way to extract BS using python code?

4
General Questions and Answers / Band Structure
« on: October 30, 2024, 15:41 »
Dear Expert,

I have attached my band structure plot, and I would like to recreate this plot using "atkpython." Is there a way to extract the necessary information using a script?

Additionally, I already have a script for the density of states of the same system, and I was wondering if it would be possible to plot both BS and DOS side by side.

Thank you!

5
You can extract alot of information
1) Spin-Dependent Conductance
2) Spin Polarization of the Current
3) Transmission Pathways
4) Magnetoresistance etc

Detail for transmission spectrum is (https://docs.quantumatk.com/manual/Types/TransmissionSpectrum/TransmissionSpectrum.html). There are alot of tutorial in quantumatk website, use keyword "transmission" to see the relavant tutorials.

6
General Questions and Answers / Re: DOS vs TS
« on: October 8, 2024, 21:49 »
Thank you Dr Blom.

The reason for using only a few k-points for the TS calculation in my case is that I have a very long stanene nanoribbon, which generally requires only a few k-points. In some cases, I observed a bigger peak in the DOS, but when I examined the transmission spectrum (TS) at zero bias for the same system, that peak was not present. To my understanding, the transmission function T(E), which can be considered a density of states (DOS) weighted by the probability of electron transfer from the device region to the left or right electrodes.

I think if I increase the number of k-points in the B direction only in stanene nanoribbon, I might observe similar peaks. For a 1D system like this, I assume that increasing k-points in the B direction should be fine??

7
General Questions and Answers / DOS vs TS
« on: October 5, 2024, 04:01 »
Dear Expert
I have attached photo for my system where I have shown you DOS and TS. In DOS, there are some peak on the fermi level but in TS its not? I dont understand this? Is a way to make TS peaks smooter like DOS attached in pics or is there a way to add broadening in TS? I want TS peak a bit smoother.

Thank you

8
General Questions and Answers / Re: Brodening in LCAO calculator
« on: September 24, 2024, 14:39 »
A follow up question on that:
I have a long stanene nanoribbon, and I am optimizing iron-tin cluster on it. My system is large in C direction so I need only few k-points, may be 1 k-point in C direction. So, I needs large broadening value?

This is what I understand from the discussion

9
General Questions and Answers / Re: Brodening in LCAO calculator
« on: September 23, 2024, 13:15 »
The default broadening value of 1000 K typically refers to the temperature used to define the width of the electronic states in energy calculations.

10
Many thanks - I got the your point.

11
Hello Experts,
I followed the tutorial on molecular devices (https://docs.quantumatk.com/tutorials/molecular_device/molecular_device.html), but I am unclear about a few steps. Specifically:

When MPSH with atom indices (37, 38, 39, 40, 41, 42, 43, 44, 45, 46) is computed, I don't understand how or why quantum numbers 13, 14, 15, and 16 are chosen in the next step.

I have my own system, as shown in the attached pictures, and I am interested in observing the overlap between tin atoms 40, 92, and 95. I've calculated MPSH, but I am unsure how to choose the correct quantum numbers for eigenstate analysis?


12
The way I approach the two-probe system optimization is by dividing it into smaller parts.  Instead of optimizing the entire device at once, which is a massive task, I find it faster and more efficient to build the device from optimized components.

I first separately optimize the central region, which in this case includes the organic molecules and similarly, optimize the gold electrodes. Then, place the optimized organic molecules between the optimized gold electrodes.

Each part is already optimized, then no need to optimize complete device again.

If you want expert comments, you should wait for a response from @Anders Blom.

13
General Questions and Answers / Re: Current at each bias
« on: September 10, 2024, 01:40 »
I got your point. Actually I was looking the following tutorial (https://docs.quantumatk.com/tutorials/std_transport/std_transport.html). I run many bias but I didnot get current using the following

 Calculate the current from the transmission spectrum
    current = transmission_spectrum.current()

14
General Questions and Answers / Re: Current at each bias
« on: September 8, 2024, 01:08 »
If I understand you correctly then it's mean I have to apply different bias let's say -0.1, 0.2 etc and calculate the TS. ok?

I calculated the TS with -0.1 and also got current as shown in the figure? this is what you are explaining?

15
General Questions and Answers / Current at each bias
« on: September 2, 2024, 15:44 »
Dear Expert,
I hope you are doing well.

I am interested in calculating the current at each bias given in code below. This code work well, but I don't have an idea how to calculate current at each bias, any suggestion?

pos_bias_list = [0.10, 0.20, 0.30, 0.40, 0.50, 0.60, 0.70]*Volt

# Read DeviceConfiguration
zero_bias_file = '/home/hartree/jem/wolf6252/N-P/Device/Fe-H-D/Fe-H-D-3-3/Fe-H-D-3-3.hdf5'
device_configuration = nlread(zero_bias_file, DeviceConfiguration)[0]

for bias in pos_bias_list:
    if processIsMaster():
        print("Bias is now: ", bias)
    # Get the calculator
    calculator = device_configuration.calculator()

    # Set the bias voltage
    calculator=calculator(electrode_voltages=(bias/2, -bias/2))

    # Attach the calculator and use the old initial state
    device_configuration.setCalculator(
      calculator(),
      initial_state=device_configuration)
    device_configuration.update()
    nlsave('device_bias_%.2f.hdf5' % bias.inUnitsOf(Volt), device_configuration)
    nlprint(device_configuration)

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