Dear Sir,
Thank you for the clarification.
Naveen
Department of Physics & Astrophysics
University of Delhi
New Delhi-110007
On Tue, Aug 13, 2019, 17:56 Anton Akhmerov <anton.akhmerov...@gmail.com>
wrote:
> Dear Naveen,
>
> These inwards- and outwards- facing leads wouldn't have translation
> invariance. This makes one unable to compute a mode decomposition in
> such a geometry, and therefore computing the conductance becomes
> extremely difficult. Right now Kwant only implements the algorithms
> that assume translationally invariant leads.
>
> Best,
> Anton
>
> On Tue, 13 Aug 2019 at 14:15, Naveen Yadav <naveengunwa...@gmail.com>
> wrote:
> >
> > Dear sir,
> >
> > syst.attach_lead(lead, origin=lat(0, 0, 0)) # lat(0, 0, 0) is in the
> hole of the annulus
> > This is okay. But I want to create leads in the radial direction,
> suppose X is the width of cylinder, Y is circumference and Z is the
> Difference in outer and inner radii. So, I want to create leads wrapped
> around Y, for inner circumference lead should directed towards origin and
> for outer circle directed away from the origin. Code for creating annulus
> geometry is given below-
> >
> > import kwant
> > import scipy.sparse.linalg as sla
> > import matplotlib.pyplot as plt
> > import tinyarray
> > import numpy as np
> > from numpy import cos, sin, pi
> > import cmath
> > from cmath import exp
> >
> > 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, L=22, r_in=22, r_out=30, t=1.0, t_x=1.0, t_y=1.0,
> t_z=1.0, lamda=0.2, beta=1.05, phi_uc = 0.0078):
> > # ring shape
> > def ring(pos):
> > (z, y, x) = pos
> > rsq = y ** 2 + z ** 2
> > return r_in ** 2 <= rsq <= r_out ** 2 and x in range (L)
> >
> > def onsite(site):
> > return (t_z * cos(beta) + 2 * t) * sigma_z
> >
> > def hoppingx(site0, site1):
> > return (-0.5 * t * sigma_z - 0.5 * 1j * t_x * sigma_x)
> >
> > def hoppingy(site0, site1):
> > return -0.5 * t * sigma_z - 0.5 * 1j * t_y * sigma_y
> >
> > def hoppingz(site0, site1):
> > y = site1.pos[1]
> > return (-0.5 * t_z * sigma_z - 0.5 * 1j * lamda * sigma_0) *
> exp(2 * pi * 1j * phi_uc * a * (y-40))
> >
> >
> > syst = kwant.Builder()
> > lat = kwant.lattice.cubic(a, norbs=2)
> > syst[lat.shape(ring, (0, r_in+1, 0))] = onsite
> > syst[kwant.builder.HoppingKind((1, 0, 0), lat, lat)] = hoppingz
> > syst[kwant.builder.HoppingKind((0, 1, 0), lat, lat)] = hoppingy
> > syst[kwant.builder.HoppingKind((0, 0, 1), lat, lat)] = hoppingx
> >
> > lead = kwant.Builder(kwant.TranslationalSymmetry((-a, 0, 0)))
> >
> > lead[lat.shape(ring, (0, r_in+1, 0))] = onsite
> > lead[kwant.builder.HoppingKind((1, 0, 0), lat, lat)] = hoppingz
> > lead[kwant.builder.HoppingKind((0, 1, 0), lat, lat)] = hoppingy
> > lead[kwant.builder.HoppingKind((0, 0, 1), lat, lat)] = hoppingx
> >
> > syst.attach_lead(lead)
> > syst.attach_lead(lead, origin=lat(0,0,0))
> > return syst
> >
> > def analyze_system():
> > syst = make_system()
> > fig = plt.figure()
> > ax = kwant.plot(syst)
> > ax.savefig('sys2.png',dpi=200)
> >
> > def main():
> > syst = make_system()
> > analyze_system()
> > main()
> >
> > On Tue, Aug 13, 2019 at 3:18 PM Joseph Weston <joseph.westo...@gmail.com>
> wrote:
> >>
> >> Hi,
> >>
> >> Dear sir,
> >>
> >> Could we attach circular leads to the inner and outer circle of annulus
> geometry in 3D? Please suggest me if there is a way to do that.
> >>
> >> What do you mean by circular leads? Do you mean leads with a circle
> cross-section (i.e. a semi-infinite cylinder lead)? If so then all you need
> to do is create a lead with a circular cross-section uses 'lat.shape' in a
> similar way to how you created the scattering region. You can attach leads
> to the interior of the annulus by specifying the parameter 'origin' to be a
> site in the interior of the annulus when calling 'attach_lead' (see the
> documentation [1]). e.g.:
> >>
> >> syst.attach_lead(lead, origin=lat(0, 0)) # lat(0, 0) is in the
> hole of the annulus
> >>
> >>
> >> Happy Kwanting,
> >>
> >>
> >> Joe
> >>
> >>
> >> [1]:
> https://kwant-project.org/doc/1/reference/generated/kwant.builder.Builder#kwant.builder.Builder.attach_lead
> >
> >
> >
> > --
> >
> >
> > With Best Regards
> > NAVEEN YADAV
> > Ph.D Research Scholar
> > Deptt. Of Physics & Astrophysics
> > University Of Delhi.
>
