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Messages - rruisan

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1
there are a finite number of atoms with which you can work to get the density of states for graphene plane? and the curved graphene any idea how that would be done to optimize not return to the plane? (use the correct configuration and topology), for this you should use ATK with tight-binding and DFT?

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Good afternoon!

I'm working on the analytical part of the changes in the curvature in graphene using DOS, but for that I have to learn physics on the plane, where I like to use the simulation as it is very interesting.

Where generate a flat graphene sheet containing 54 carbon atoms, to plot the energy compared to DOS gives me the following image (see DOS-DFT).

Furthermore Tight Binding model is an approximation to nearest neighbors periodically, where you have a Hamiltoniao where the diagonalized gives us the eigenvalues ​​which has been corroborated by the experimental part (taken from reference articles), we have that graph of the density of states on energy gives us (see Dos-Dirac.jpg), where you can appreciate the Dirac points where the dirac point enclosed in a box (this can be seen with the zoom where the arrow points) .

My question is why in the two images that I show can not see a similarity in the two approaches to get a sense that both are equal, or if there is any way that the simulation with DFT, can visualize the Dirac points and find that energy is linear for flat graphene as shown Dos-Dirac.jpg. Then I need to do?

Now to make the slightly curved graphene. For explanations of other pots of Ander Blom and Umberto Martinez, disclose that is only an approximation because it is not considered an accurate topology and parameters. So that by optimizing the geometry, it resulted in the plane.

  Is there any way to put the correct parametriazación and the exact topology for the shape of the graph Dos.jpg? in which case you can, as you can do? in order to see if there are any changes in the graphical DOS with curvature. Sorry if this is very basic for you, but still have not found the answer I'm looking into articles.

Another question, How can calculate the magnetic susceptibility as a function of temperature using DFT? Thanks in advance for directing me!

3
thank you very much for help, but I do not get even, I believe that I have enough experience using this excuse. Try playing the two images you put,
in the first image you place, when repeated'm not understanding to do this (as used?), do so and get this


In the second image you can, just try to do so, by making the nano sheet, use swap axes X to Y, then put what you show in the image (depending on z). I would appreciate if you can tell me more detail or if you can suggest me where I can see this in some video. Thanks in advance!.

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Dear Anders,

thank you very much for the guidance, I'm trying to recreate the ripples of graphene pots which he called "Fun with Graphene" as it has the Gaussian shape, but not values ​​should take "Buckler" I have moved other values ​​but keep getting weird stuff . I would appreciate s can you tell me, how I should change the values​​?

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Plugin Development / Re: Fun with graphene
« on: August 26, 2014, 18:59 »
What values ​​should I wear for generate the ripples? So that resembles reality! there is a tutorial that explains it, please!

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Plugin Development / Re: Fun with graphene
« on: August 26, 2014, 18:50 »
I mean to create ripples values ​​take the amplitude, periodicity or angle or all variables to consider.

7
Plugin Development / Re: Fun with graphene
« on: August 26, 2014, 18:27 »
Dear Anders!


Thank you very much for the clear explanation, I thank you, just one last question with this topic, for the ripples in graphene, there any tutorial to tell me how I change the parameters being Coordinate Open Tools> Buckler or Twister.  Thank you very much for the kind patience you have me.

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Plugin Development / Re: Fun with graphene
« on: August 25, 2014, 19:12 »
I do not understand, once the zip file in AddOn Manager installed. Being on Builder, where I see the ripples in graphene and other example he gives? Thanks in advance!

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Plugin Development / Re: Fun with graphene
« on: August 25, 2014, 08:17 »

Dear Anders,

what happens is that I did not know where it was installed the folder and so I put in examples, but I've seen that has installed this direction (), where I followed the instructions in the beginning of this post. What I still do not see! it's like opening plugins.py as I headed to "Builder- Add", but go the route that I put in (), says error when I want to open some plugins.py. If there is a post that explains me to do, grateful if you tell me please apologize for the inconvenience!



Many thanks!

10
Plugin Development / Re: Fun with graphene
« on: August 24, 2014, 02:13 »
Dear Anders,

I followed the installation step of the .zip, after installing, I put the unzipped folder in VNL / examples /. After I opened the Virtual Nanolab, directs me to tools-custom-builder, opened the folder FunWithGraph I chose one at random but generates nothing. I would appreciate your guidance!

11
I can help to create the right, please? or can you tell me, if I can take some example put (TubeBuilder.py) and change the lines to get what I want!
Thanks in advance!

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Good day, I'm still trying to do the Gaussian structure of graphene, I started doing this:

import numpy as np

def makeGaussian(size, fwhm = 3, center=None):
    """ Make a square gaussian kernel.
    size is the length of a side of the square
    fwhm is full-width-half-maximum, which
    can be thought of as an effective radius.
    """

    x = np.arange(0, size, 1, float)
    y = x[:,np.newaxis]

    if center is None:
        x0 = y0 = size // 2
    else:
        x0 = center[0]
        y0 = center[1]

    return np.exp(-4*np.log(2) * ((x-x0)**2 + (y-y0)**2) / fwhm**2)

 # find width of gaussian
    configuration = NanoSheet(n,m)
    lattice = configuration.bravaisLattice()

# now extract the information about the configuration
    lattice = configuration.bravaisLattice()
    elements = configuration.elements()
    cartesian_coordinates=configuration.cartesianCoordinates().inUnitsOf(Angstrom)

# gaussian parameters group
builder.newGroup('gaussian parameters')
builder.integer( 'n', 8, 'n', min=1, max=1000)
builder.integer( 'm', 0, 'm', min=0, max=1000)
   
to run it does not work, would appreciate if you can guide me or tell me the correct way you can get me.

13
General Questions and Answers / Re: TubeBuilder.py
« on: April 14, 2014, 03:05 »
buenas tardes la respuesta lo obtengo de un post que escribí con una duda acerca de môbius.py donde me da la respuesta Anders Blom, solo que no habia visto donde se encuentra el icono "Custom Builder", entonces la parte gráfica, lo visualizo estando en la ventana Virtual NanoLab-Tools-Custom Builder, y ya conoce abro el documento y le .cif lo extraigo de la parte gráfica que ahora si tengo.

Saludos!

14
General Questions and Answers / TubeBuilder.py
« on: April 11, 2014, 01:08 »
Buenos días, una disculpa por redactar en español no soy muy bueno escribiendo en ínlges. Trate de usar TubeBuilder.py pero para eso me pedia tener el Twister.py el cual baje y lo deje en la carpeta de quantuwise/atk-13.8/vnl/lib/phyton-2.7/sites-packages donde también deje TubeBuidler.py  lo quise abrir con Builder-Add-from files, pero no se pudo abrir y me sale la siguiente inidicación


No supported configurations in file:
/home/richie/QuantumWise/atk-13.8.1/vnl/lib/python2.7/site-packages/TubeBuilder.py

Les agradecería su orientación, para poder usar el modo gráfico o si alguien me puede enviar la extesión .CIF. Gracias de antemano.

15
Thanks for the prompt reply! is there any tutorial? explain to me how to do the script or algorithm of the function, for example to generate the Mobius strip of parameterized Môbius.py not see how to generate the structure. This type of script (Môbius.py) help me? create the role I want to play. Thanks in advance!

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