Re: [Kwant] Spin

So this means your Kwant installation is broken. What is the OS? How did you install Kwant? What does import kwant; kwant.test() return? Best, Anton On Thu, Jun 25, 2015 at 1:34 PM, Alexis Bozio wrote:

Hi Anton, Thank you for awnsering! I don't think that it is e problem with my code because there because i am using the one that is used on the tutoring of kwant:

import kwant

# For plotting from matplotlib import pyplot

# For matrix support import tinyarray

# define Pauli-matrices for convenience sigma_0 = tinyarray.array([[1, 0], [0, 1]]) sigma_x = tinyarray.array([[0, 1], [1, 0]]) sigma_y = tinyarray.array([[0, -1j], [1j, 0]]) sigma_z = tinyarray.array([[1, 0], [0, -1]])

def make_system(a=1, t=1.0, alpha=0.5, e_z=0.08, W=10, L=30): # Start with an empty tight-binding system and a single square lattice. # `a` is the lattice constant (by default set to 1 for simplicity). lat = kwant.lattice.square(a)

sys = kwant.Builder()

#### Define the scattering region. #### sys[(lat(x, y) for x in range(L) for y in range(W))] = \ 4 * t * sigma_0 + e_z * sigma_z # hoppings in x-direction sys[kwant.builder.HoppingKind((1, 0), lat, lat)] = \ -t * sigma_0 - 1j * alpha * sigma_y # hoppings in y-directions sys[kwant.builder.HoppingKind((0, 1), lat, lat)] = \ -t * sigma_0 + 1j * alpha * sigma_x

#### Define the left lead. #### lead = kwant.Builder(kwant.TranslationalSymmetry((-a, 0)))

lead[(lat(0, j) for j in xrange(W))] = 4 * t * sigma_0 + e_z * sigma_z # hoppings in x-direction lead[kwant.builder.HoppingKind((1, 0), lat, lat)] = \ -t * sigma_0 - 1j * alpha * sigma_y # hoppings in y-directions lead[kwant.builder.HoppingKind((0, 1), lat, lat)] = \ -t * sigma_0 + 1j * alpha * sigma_x

#### Attach the leads and return the finalized system. #### sys.attach_lead(lead) sys.attach_lead(lead.reversed())

return sys

def plot_conductance(sys, energies): # Compute conductance data = [] for energy in energies: smatrix = kwant.smatrix(sys, energy) data.append(smatrix.transmission(1, 0))

pyplot.figure() pyplot.plot(energies, data) pyplot.xlabel("energy [t]") pyplot.ylabel("conductance [e^2/h]") pyplot.show()

def main(): sys = make_system()

# Check that the system looks as intended. kwant.plot(sys)

# Finalize the system. sys = sys.finalized()

# We should see non-monotonic conductance steps. plot_conductance(sys, energies=[0.01 * i - 0.3 for i in xrange(100)])

# Call the main function if the script gets executed (as opposed to imported). # See http://docs.python.org/library/__main__.html. if __name__ == '__main__': main()

Best Regards,

Alexis

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From: anton.akhmerov@gmail.com Date: Thu, 25 Jun 2015 11:28:58 +0200 Subject: Re: [Kwant] Spin To: alexis-bozio@hotmail.fr CC: kwant-discuss@kwant-project.org

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Hi Alexis,

Can you share the code that you wrote? Is there any error being raised?

Can you check if your kwant installation is working? To do so execute

import kwant kwant.test()

and check the output.

Best, Anton

On Thu, Jun 25, 2015 at 11:25 AM, Alexis Bozio wrote:

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Hello,

I'm trying to calculate transmission function including spin with Matrix for onsite values but when i am writting the code that is explained on the site (http://kwant-project.org/doc/1.0/tutorial/tutorial2) it makes the calculation but a few seconds later Python stops and all the datas vanishe. Thank you for your help. Best Regards. Alexis Bozio