Dear Kwant users,

In Kwant manual there is a section entitled "Calculating spectral density with the kernel polynomial method". I find that examples in this section are all talking about finite-size systems. I wonder whether Kwant can calculate density of states of a quasi one-dimensional system that is finite along y-direction but is translationally invariant along x-direction. For a minimal test, I have run the following codes but errors occurred.

#--------------------------------------------------------------------------------------

import kwant

import numpy

a=1

W=30

t=1

lat = kwant.lattice.square(a)

syst = kwant.Builder(kwant.TranslationalSymmetry((-a, 0)))

syst[(lat(0, j) for j in range(W))] = 4 * t

syst[lat.neighbors()] = -t

fsyst = syst.finalized()

energies = numpy.linspace(-0.1,0.1, 10)

spectrum = kwant.kpm.SpectralDensity(fsyst)

spectrum.add_moments(10)

spectrum.add_vectors(5)

densities = spectrum(energies)

#--------------------------------------------------------------------------------------

What's wrong in above codes? Currently, are we able to employ Kwant to calculate density of states of 3D systems being translationally invariant along one or two directions?

Regards,

Zhan