Messages

16

General Questions and Answers / Simple graphene nanoribbon inelastic transmission spectrum

« on: October 9, 2019, 17:13 »

Hi

I've tried the transmission spectrum of a simple zigzag graphene nanoribbon and obtained the transmission spectrum as expected. I now want to compute the inelastic transmission spectrum (i.e. transmission spectrum with the effects of phonons), how can I make this calculation in QuantumATK?

Thanks in advance...

17

General Questions and Answers / Re: 3D scene atomic connection lines cracked

« on: June 1, 2018, 13:55 »

You're not helpful at all here. I think you don't know the answer and also taking this as an opportunity for pushing to buy a new version. I don't need new features, as most other users don't (take a look at the recent publications, 95% of them can be simulated even using Version 11.2: https://docs.quantumwise.com/scientificpublications/listofpublications.html) and I don't have a few thousand Euros project budget to buy a new version for getting a few new pseudopotentials...

1. What is the support period for Quantumwise products? Do I need to pay each year in order to get free support on this forum?
2.  " It may not be fully compatible with the Windows 10 operating system and/or your hardware." Sorry but this is a nonsense comment on a technical forum.  I don't expect may not be... sentences. Don't you know the compatibilities of your products. Or does it mean that because I have bought my product 4 years before, I shouldn't expect any helpful answer?
3. I'm using 2014.3 version and this version was released on 21 July 2015: https://quantumwise.com/about-us/quantumwise-news/item/894-update-vnl-atk-2014-3-released.  Windows 10 was released on 29 July 2015. Therefore the OS compatibility argument is weird.
4. I think you shouldn't take questions like this as an opportunity to try to push your customers to upgrade to a new version. When I buy 2018.0 and I experience a problem in 2020, you'll recommend to upgrade to the 2020 version. This is ridiculous.

Quantumwise AS were being a friendly company with core developers like Anders Blom and Kurt Stokbro questions answering even the silliest questions on this forum back on 2009-2010. A lot have changed since then obviously... even when Quantumwise is now a part of Synopsys...

18

General Questions and Answers / Re: 3D scene atomic connection lines cracked

« on: June 1, 2018, 06:50 »

1. This happens in any structure, lines that denote bonds seem cracked in the scene.
2. I'm using VNL 2014.3 64-bit on Windows 10 64-bit.
3. My graphics card is AMD Radeon 5570 and its drivers are correctly installed.
4. The graphics ofall games, apps etc. are OK on my PC except the VNL scene.

Thanks.

19

General Questions and Answers / 3D scene atomic connection lines cracked

« on: May 31, 2018, 15:10 »

Hi,

In VNL, the lines showing the atomic bonds seems cracked in whatever I build as shown in the attached figure below. Do I need to install some driver to make the VNL scene seem as expected?

Thanks.

20

General Questions and Answers / Re: How to build a borophene nanoribbon correctly in VNL?

« on: May 22, 2018, 19:10 »

Hi Peter

I followed this order: Add->From plugin->Nanoribbon and then selected Boron for the elements however I couldn't replicate the structure shown in the paper.

I hope ypu can help me building this.

Thanks a lot.

21

General Questions and Answers / How to build a borophene nanoribbon correctly in VNL?

« on: May 19, 2018, 17:22 »

Dear sirs

I am trying to build a borophene nanoribbon in VNL as reported in the attahced paper. However the borophene nanoribbon VNL creates is wrong (the attached figure) according to the reported geometry in the paper. How can I build a correct borophene nanoribbon in VNL?

(The paper reporting the correct porophene nanoribbon is: https://link.springer.com/content/pdf/10.1007%2Fs40820-017-0167-z.pdf)

Thanks.

22

General Questions and Answers / Re: Simulation of simple quantum computation concepts in ATK

« on: July 30, 2017, 21:08 »

Yes.

23

General Questions and Answers / Simulation of simple quantum computation concepts in ATK

« on: July 22, 2017, 12:32 »

Hi

I just wondered if there's an example or a case study in which simple quantum computational concepts are simulated in ATK? Is there a possibility to simulate quantum computational concepts in ATK at a molecular level?

Thanks a lot...

24

General Questions and Answers / Re: Bloch state velocity in silicene = 0 !!!

« on: March 14, 2017, 21:47 »

Thanks a lot for your help.  These were very helpful.

25

General Questions and Answers / Re: Bloch state velocity in silicene = 0 !!!

« on: March 14, 2017, 20:10 »

Dear Petr Khomyakov
Thanks a lot for your explanations, really helpful. However when I print the V_y of the graphene sheet with the following code, ATK gives 3.42x10^2m/s which is far lower than V_x (=8.37x10^5m/s). What can be the reason of this big difference?

Code

# -------------------------------------------------------------
# Bulk configuration
# -------------------------------------------------------------

# Set up configuration
bulk_configuration = BulkConfiguration(
    bravais_lattice=Hexagonal(2.4612*Angstrom, 6.709*Angstrom),
    elements=[Carbon, Carbon],
    fractional_coordinates=[[ 0.333333333333,  0.166666666667,  0.5 ],
                            [ 0.666666666667,  0.833333333333,  0.5 ]],
    )

# -------------------------------------------------------------
# Calculator
# -------------------------------------------------------------
calculator = LCAOCalculator()

bulk_configuration.setCalculator(calculator)
nlprint(bulk_configuration)
bulk_configuration.update()

# Fractional k-point, slighly displaced away from the Dirac point.
k = [1./3+0.001, 1./3+0.001, 0  ]

# Calculate the velocity of the band with band-index 3 (valence band) 
velocity = calculateVelocity(bulk_configuration, kpoint=k, spin=Spin.Up, band_indices=[3])
# Take the velocity component along the X cartesian direction.
velocity = velocity[0][0][1]

# Print the result.
print 'Fermi velocity of graphene:'
print 'v = %.2e m/s' %abs(velocity.inUnitsOf(Meter/Second))

Thanks.

26

General Questions and Answers / Re: Bloch state velocity in silicene = 0 !!!

« on: March 14, 2017, 17:01 »

I tried the velocity[0][0][1] and velocity[0][0][2] expressions in the original graphene example and it gives 0 or very low numbers.  I think the Bloch state velocity should be same in x and y directions in a graphene sheet. Then how do I get velocities in y-direction for the original graphene sheet (and z direction for GNR-like 1-D structures)? I couldn't get it from the manual at http://docs.quantumwise.com/manuals/Types/calculateVelocity/calculateVelocity.html. Thanks.

27

General Questions and Answers / Re: Bloch state velocity in silicene = 0 !!!

« on: March 14, 2017, 16:31 »

Sorry, I'm a novice in this subject. The velocity output of the calculateVelocity function returns velocities for each band so velocity[0][0][0] gives the velocity in bands 0, 0,0, it this true? Then how do I calculate the velocity in z direction? Is it velocity[0][0][1]? Thanks a lot.

28

General Questions and Answers / Re: Bloch state velocity in silicene = 0 !!!

« on: March 14, 2017, 15:19 »

I'm sorry for my mistake, my structure was not silicene. It is a silicene nanoribbon (SiNR). In this case, which k-point should I use for the calculation of Bloch state velocity? Instead of k = [1./3, 1./3, 0] according to the bandstructure given below:



Thanks in advance...

29

General Questions and Answers / Re: Bloch state velocity in silicene = 0 !!!

« on: March 14, 2017, 12:03 »

Dear zh

The bandstructure is as follows:



Thanks a lot...

30

General Questions and Answers / Bloch state velocity in silicene = 0 !!!

« on: March 14, 2017, 10:27 »

Dear sirs

I tried the "Bloch state velocity of graphene" example (http://docs.quantumwise.com/manuals/Types/calculateVelocity/calculateVelocity.html) in ATK and it worked as expected. However, I adapted the code to calculate the Bloch state velocity in silicene but the script gives "v = 0.00e+00 m/s". I'll be happy if you could say what I'm doing wrong in my code:

Code

# Set up lattice
vector_a = [10.0, 0.0, 0.0]*Angstrom
vector_b = [0.0, 27.52, 0.0]*Angstrom
vector_c = [0.0, 0.0, 3.79319126858]*Angstrom
lattice = UnitCell(vector_a, vector_b, vector_c)

# Define elements
elements = [Silicon, Silicon, Silicon, Silicon, Silicon, Silicon, Silicon,
            Silicon, Silicon, Silicon, Hydrogen, Hydrogen]

# Define coordinates
fractional_coordinates = [[ 0.485470918896,  0.182646995637,  0.            ],
                          [ 0.548086613279,  0.21992408583 ,  0.5           ],
                          [ 0.496179292117,  0.300404683423,  0.5           ],
                          [ 0.551593763211,  0.340364254506,  0.            ],
                          [ 0.494273148721,  0.420353418505,  0.            ],
                          [ 0.549308621502,  0.460381450687,  0.5           ],
                          [ 0.494925490948,  0.540461848335,  0.5           ],
                          [ 0.552265117634,  0.579881857971,  0.            ],
                          [ 0.492744063004,  0.659628645016,  0.            ],
                          [ 0.542868494137,  0.699147125462,  0.5           ],
                          [ 0.503460722888,  0.751973737953,  0.5           ],
                          [ 0.508748721009,  0.128517272588,  0.            ]]

# Set up configuration
bulk_configuration = BulkConfiguration(
    bravais_lattice=lattice,
    elements=elements,
    fractional_coordinates=fractional_coordinates
    )

numerical_accuracy_parameters = NumericalAccuracyParameters(
    interaction_max_range=10.0*Angstrom,
    k_point_sampling=(10, 10, 10),
    )

calculator = LCAOCalculator(
    numerical_accuracy_parameters=numerical_accuracy_parameters,
    )
bulk_configuration.setCalculator(calculator)
nlprint(bulk_configuration)
bulk_configuration.update()

# Fractional k-point, slighly displaced away from the Dirac point.
k = [1./3, 1./3, 0  ]

# Calculate the velocity of the band with band-index 3 (valence band) 
velocity = calculateVelocity(bulk_configuration, kpoint=k, spin=Spin.Up, band_indices=[3])
# Take the velocity component along the X cartesian direction.
velocity = velocity[0][0][0]

# Print the result.
print 'Fermi velocity of silicene:'
print 'v = %.2e m/s' %abs(velocity.inUnitsOf(Meter/Second))

Thanks in advance.
Narin