eycomb? the
> hoppings along x and y direction are more complicated in honeycomb.
> Regards,
> Qingtian Zhang
>
--
Abbout Adel
import kwant
from matplotlib import pyplot
import tinyarray
from numpy import sqrt
sigma_0 = tinyarray.array([[1, 0], [0, 1]])
Sigma_z
Dear all,
I have two simple questions concerning electronic transport with spins with
no interaction:
If I take the program spin_orbit.py from the tutorial and call the system
sys=make_system ( alpha=0, ez=0, W=2, L=2)
# no spin orbit interaction
print matrix.round
related question
> http://thread.gmane.org/gmane.comp.science.kwant.user/77
>
> Best regards,
> Anton Akhmerov
>
>
> On Sat, Mar 8, 2014 at 8:09 AM, Abbout Adel wrote:
>
>>
>>
>> Dear all,
>> I have two simple questions concerning electronic transport with
he wavefunction of the system by using
> ham = sys.hamiltonian_submatrix()
> evecs = la.eigh(ham)[1]
>
> Is the wavefunction corresponding to site i given by evecs[i] ? Thanks!
>
> Best,
> Johnny
>
> On 18 April 2016 at 03:44, Abbout Adel wrote:
>
>
t; plotted by
>
> kwant.plot(sys, site_color=wf, site_symbol=family_shape,
>site_size=0.5, hop_lw=0, cmap='gist_heat_r')
>
> can be obtained from wf without attaching the leads right? Thanks again
> for your time.
>
> Best,
> Johnny
>
> On 18 April 2
on).
>>>>
>>>> Best,
>>>> Anton
>>>>
>>>> On Thu, May 5, 2016 at 9:48 PM, Sergey wrote:
>>>>
>>>>> Dear all,
>>>>> I want to model a random variation of hopping integrals. Simply
>>>>> writing:
>>>>>
>>>>> def hopping(sitei, sitej):
>>>>> return -1 + random.gauss(0,0.2)
>>>>>
>>>>> does not work since this does not ensure that the hopping is
>>>>> Hermitian.
>>>>> Is there a smart way to write something like:
>>>>> def hopping(sitei, sitej):
>>>>> if sitei>>>> return -1 + random.gauss(0,0.2)
>>>>> else: return Conjugate(hopping(sitej,sitei))
>>>>>
>>>>> ?
>>>>> Thanks and best wishes,
>>>>> Sergey
>>>>>
>>>>
>>>
>
--
Abbout Adel
losed system
> with periodic boundary conditions in y-direction (I did it by hand) and
> hard-wall in x-direction. I guess I need to do the Fourier transform in
> y-direction by hand. Or, are there some built-in functions to do this?
>
> Thank you for eventual answer or pointing me to duplicate question.
>
> Tibor
>
--
Abbout Adel
ies - V0)/hbar**2)
> T = 4*k1*k2/(k1+k2)**2
> T[energies <= V0] = 0
>
> plt.figure()
> plt.plot(energies, data, energies, T)
> plt.legend(('numerical','exact'), loc=4)
> plt.xlabel("energy [V0]")
> plt.ylabel("Transmission")
> plt.show()
> return data, T
>
>
> # In[6]:
>
> stepNumerical, stepExact = plot_conductance(sys,linspace(1e-9,2*V0,201))
>
>
> # In[7]:
>
> print(stepNumerical)
>
>
--
Abbout Adel
sense given the periodic lattice.
>
> -Leon
>
> From: Abbout Adel
> Date: Monday, October 17, 2016 at 11:58 AM
> To: "Leon Maurer (lmaurer)"
> Cc: "kwant-discuss@kwant-project.org"
> Subject: [EXTERNAL] Re: [Kwant] a step tripping up Kwant
>
> Dear Le
>
>
> lat = kwant.lattice.honeycomb()
>
> a,b=lat.sublattices
>
> sym_sys = kwant.TranslationalSymmetry((1, 0))
>
> sys = kwant.Builder(sym_sys)
>
> sys[lat.shape(ribbon_shape, (0, 0))] = onsite
>
>
>
> sys[lat.neighbors()] = hopping
>
> sys[a(0, w/2), b(0, -w/2-1)] = p.t #connect the ends
>
> kwant.plot(sys)
>
> sys=sys.finalized()
>
> kwant.plotter.bands(sys,args=[p],momenta=600)
>
>
>
>
--
Abbout Adel
lat_down(i,i)).
>
>
>
> This was easy to do, when I used matrices for spin, but now that I have
> implemented it using two lattices instead I don’t know how to do it. If I
> use the same approach as before, I get two values for each (spatial)
> lattice point, and the result looks com
gt;
>
> # Check that the system looks as intended.
>
> # kwant.plot(sys)
>
>
>
> # Finalize the system.
>
> sys = sys.finalized()
>
>
>
> en = 3
>
> sm = kwant.smatrix(sys, en)
>
>
>
> print('transmission by kwant: ',sm.transmission(0,0))
>
>
>
> smatrix = sm.data
>
> sdags = (smatrix.conj().T)
>
> # As from Eq. (10) in kwant paper
>
> print((sdags[0,0]*smatrix[0,0] + sdags[0,1]*smatrix[0,1] +
> sdags[1,1]*smatrix[1,1]+ sdags[1,0]*smatrix[1,0]))
>
> # As from Eq. (47) in buttiker
>
> print(sdags[0,0]*smatrix[0,0]+sdags[1,1]*smatrix[1,1] - 2)
>
>
>
> # 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()
>
--
Abbout Adel
will be greatly
> appreciated. Thank you.
>
>
>
>
> --
> Oliver B. Generalao
>
> M.S. Physics student
> Structure and Dynamics Group
> National Institue of Physics
> University of the Philippines
> Diliman, Quezon City
> Trunkline: +63-2-981-8500
> Mobile: +63-927-4033966
>
--
Abbout Adel
ersampling=1)
>
> syst = make_system()
> kwant.plot(syst)
> syst = syst.finalized()
> plot_conductance(syst, energies=[-0.25 + 0.005 * i for i in range(100)])
> plot_wave_function(syst)
>
>
> Currently, I get the error "The number of sites doesn't match the number
> of provided values."
>
> Thanks,
> Eric
>
>
--
Abbout Adel
or the rectangle barrier in Kwant?
>
> Best regards,
> Kristjan
>
> [1] - https://en.wikipedia.org/wiki/Rectangular_potential_barrier
>
> [2] - http://pastebin.com/jq7CKfSP
>
>
>
>
--
Abbout Adel
else 0.
> Is there any example code from which I can learn to use this function?
>
>
> Best,
> Dongwook.
--
Abbout Adel
bove a 2D
> system?
> I'm guessing that I have to use a 3D system where the system is in the XY
> plane and the lead has a translational symmetry in the Z direction.
>
> Thanks,
> Eric
>
--
Abbout Adel
t;
> Thank you for the quick reply. I think my institute mail is not working
> properly, so I used this mail-id.
>
> By using the line: lambda site: sys_2['sys'][site]
>
> I got another error massage, which says that, "TypeError: 'int' object is
> not callable".
>
> With regards,
> Sudin
>
>
> --
> সুদিন
>
--
Abbout Adel
> >> Tómas
> >>
> >> On Fri, Jan 6, 2017 at 3:46 PM, Camilla Espedal
> >>
> >> wrote:
> >>>
> >>> Hi again,
> >>>
> >>>
> >>>
> >>> This question is basically the same as this:
> >>> https://www.mail-archive.com/kwant-discuss@kwant-project.org/msg0007
> >>> 6
> >>> .html
> >>>
> >>>
> >>>
> >>> I want to calculate some things using the scattering matrix. I
> >>> started out with a very simple system, most basic two-terminal
> >>> system. For some energy there is one propagating mode. I now add
> >>> matrix structure to the mix (just multiply by s_0 everywhere) and
> >>> there are now 2 propagating modes (which makes sense).
> >>>
> >>>
> >>>
> >>> Now, if I look at the reflection coefficients for lead 0 by using
> >>> submatrix(0,0), it is now a 2x2 matrix after I introduced the
> >>> matrices. How are the elements ordered? Is it
> >>>
> >>>
> >>>
> >>> [[r_upup, r_updown],[r_downup, r_downdown]]
> >>>
> >>>
> >>>
> >>> I know that I could make two lattices, but since I do not plan to
> >>> use the other functions such as transmission. I just want the smatrix.
> >>>
> >>>
> >>>
> >>> Hope you can help me, and thanks in advance.
> >>>
> >>>
> >>>
> >>> Best regards,
> >>>
> >>> Camilla
> >>
> >>
>
>
--
Abbout Adel
if sys[site]==edge_potential:
> return 'green'
> else: return 'black'
>
> def site_size(site):
> if sys[site]==edge_potential:
> return 0.35
> else:return 0.2
> kwant.plot(sys,site_color=family_color,site_size=site_size)
> # Finalize the system.
> sys = sys.finalized()
>
>
> # Compute number of neighbors
> i=sys.sites.index(graphene(5,6))
> all_the_neighbors=sys.graph.out_neighbors(i)
>
>
>
> # Call the main function if the script gets executed (as opposed to imported).
> # See <http://docs.python.org/library/__main__.html>
> <http://docs.python.org/library/__main__.html>.
> if __name__ == '__main__':
> main()
>
>
>
--
Abbout Adel
l to the barrier). Could you give me some advice on how
> to achieve this?
>
> Best regards,
> Kristjan
>
> On Mon, Dec 19, 2016 at 8:15 PM, Abbout Adel
> wrote:
>
>>
>>
>> Dear Kristjan,
>>
>> >>> " And the conductance is the s
solve it easily. your conductance is the sum of all the
conductances (Actually the sum is an integral (you need to divide over
the number of modes to go from the sum to the Riemann integral))
I hope that this helps
Adel
On Tue, Feb 14, 2017 at 2:36 PM, Abbout Adel wrote:
> Dear Krist
> me.
>
> The inverse of the left-hand side matrix produced by
> make_linear_system in Kwant is the Green's function, i.e. it already
> includes the relevant self-energy. However computing the complete
> Green's function is extremely inefficient. Can you please be more
> specific: do you perhaps need only some matrix elements of the Green's
> function? What observable is your final goal?
>
> Best,
> Anton
>
> >
> >
> > Sincerely,
> >
> >
> > Hu Yongliang
> >
> >
> >
> >
>
--
Abbout Adel
over the KWANT limit (as we get some delta-like peak
> around E_f), but perhaps that is too much to ask.
>
>
>
> Finally we return to the full expression for finite bias and finite T:
>
>
>
> G = 2e^2/h \int{dE T(E) d(f_L(E) - f_R(E))/dVsd}
>
>
>
> I suppose ev
om the post referenced at the start, and it
> gives a syntax error. I'm not really sure how to fix it as it looks fine to
> me. What's wrong there?
>
> And more importantly, once this is fixed, how can one then make a
> kwant.plotter.map type of plot at this x-z plane?
>
--
Abbout Adel
the formatting is all messed
>> up. Please submit any scripts as actual attachments which run and
>> produce what you wish to show. Only inline *relevant snippets* into the
>> body of the email; not a whole script. This greatly reduces the amount
>> of effort people have to go through to help out.
>>
>> Happy Kwanting,
>>
>> Joe
>>
>
>
--
Abbout Adel
Thank you Joseph for the highlight. It make sens since the tests on a
square lattice seemed working fine.
I checked the 'plot_2d_bands' function but could not identify the
transformation you were mentioning. Could you help me in this please?
Just to check my understanding for this module, could
)
> > with this, we obtain the Hamiltonian of the wrapped system
> >
> > am I correct ?
>
> Yes, in addition to the caveat that inter-cell hoppings between a site
> and its image under the symmetry will correspond to *onsite* terms in
> the wrapped around system (imagine a simple chain of sites with
> nearest-neighbor hoppings).
>
> Happy Kwanting,
>
> Joe
>
--
Abbout Adel
warning in the Kwant tutorial about this exact topic [1].
>> Any value function used by leads *must* have the declared symmetry
>> of the lead -- Kwant evaluates the lead Hamiltonian over an arbitrary
>> unit cell, so you will not get what you expect if your value functions
>> do not satisfy this symmetry.
>>
>> Do you think that we could make this warning more prominent in the
>> tutorial?
>>
>>
>> Happy Kwanting,
>>
>> Joe
>>
>>
>> [1]: https://kwant-project.org/doc/1/tutorial/tutorial2#spatially
>> -dependent-values-through-functions
>>
>
>
--
Abbout Adel
e styles? It can be useful for controlling errors when
> building the geometries with hoppings between second-neighbors...
>
> Sincerely,
> Jambulat
>
--
Abbout Adel
tes[0]] = 1
>>
>> kwant.plot(syst)
>> -
>>
>> Of course it's now your responsibility to specify the Hamiltonian,
>> leads, attaching leads, etc.
>>
>> Best,
>> Anton
>>
>> On Thu, Jul 6, 2017 at 4:12 PM, Patrik Arvoy wrote:
>> >
>> > Dear users and developers,
>> >
>> > I was wondering if I can import the coordinates of a scattering region
>> > without any particular symmetry and compute the conductance via kwant.
>> > If yes, how does one do that?
>> > Let's say the scattering region does not have any symmetry after
>> optimizing
>> > the structure via MD or ... and I have a list of coordinates of all the
>> > sites.
>> > I appreciate any help.
>> >
>> > Regards
>> > Patrik
>>
>
>
--
Abbout Adel
Dear All,
I was consulting the example of the current in a *closed system* and I am a
little bit confused:
The figure showing the current flowing inside a circle [1] is obtained for
a magnetic field B=0 !
But we know that for B=0, the Hamiltonian is a real symmetric matrix and
thus diagonalized
mentation that the same problem can arise in other
> contexts.
>
> In the future we want to make it easier to work with these different
> quantities without having to put the burden of bookkeeping on the user, but
> it's difficult to do this while trying to keep things simple. If anybody
> has any suggestions we are very open to them!
>
> Happy Kwanting,
>
> Joe
>
>
> [1]: https://kwant-project.org/doc/1/tutorial/operators#using-
> bind-for-speed
>
>
--
Abbout Adel
+1)] = e1*sigma_0
> up_lead[lat2.neighbors()] = t0*sigma_0
> syst.attach_lead(up_lead)
>
> system=kwant.plot(syst, site_lw=0.1, site_color=family_color,
> hop_lw=hopping_lw)
>
>
> trans=True
> if trans:
> syst = syst.finalized()
> energies = []
> datau = []
> datad = []
>
> for ie in range(-320,520):
> energy = ie * 0.001
> smatrix = kwant.smatrix(syst, energy=energy)
> energies.append(energy)
> Gu=smatrix.transmission((1, 0), 0)
> Gd=smatrix.transmission((1, 1), 0)
> datau.append(Gu)
> datad.append(Gd)
>
> fig = pyplot.figure()
> pyplot.plot(energies, datau, 'r--')
> pyplot.plot(energies, datad, 'b:')
> pyplot.legend(['Gu', 'Gd'], loc='upper left')
> pyplot.xlim([-0.4,0.65])
> pyplot.ylim([-0.03,1.0])
> pyplot.show()
>
>
>
--
Abbout Adel
Dear all,
In the section "Computing local quantities: densities and currents", the
function field_direction(pos,r0,delta) is defined with the condition:
if r==0: m_i=[0,0,1]
This should be m_i =[0,0,-1]
This explains why we get some strange pattern in the present figures on the
online docume
; range(3)])
> voltage = linalg.solve(cond, [1, -1, 0])
>
> How do I calculate the conductance then?
>
> Regards
> Patrik
>
> On 27 July 2017 at 17:13, Abbout Adel wrote:
>
>> Dear Patrik,
>>
>> I have some remarks for you:
>>
>> 1) In the d
ad.finalized())
>
> #finalize the system for conductivity computation
> sys=sys.finalized()
> return energies,kwant.smatrix(sys,0.0001).transmission(1,0)
>
> das=np.linspace(0,10,51)
>
> ts=[]
> defect=[1000]
> #energies,data,t=conduct(mu=0.0,da=0.0)
> #pyplot.plot(energies,data)
> for tda in das:
> energies,t=conduct(mu=0,da=tda)
> ts.append(t)
>
> #plot the conductance
>
>
>
>
>
> #pyplot.ylim([0,1])
> pyplot.show()
> pyplot.figure()
> pyplot.plot(das,ts)
> pyplot.xlabel('A')
> pyplot.ylabel('conductance[e^2/h]')
>
>
> Best regards,
> Feng Liu
>
>
--
Abbout Adel
potential(site, pot)
>> >
>> > sys[(lat(x, y) for x in range(L) for y in range(W))] = onsite
>> > sys[lat.neighbors()] = -t
>> >
>> > Define and attach the leads. ####
>> > lead = kwant.Builder(kwant.TranslationalSymmetry((-a, 0)))
>> > lead[(lat(0, j) for j in range(W))] = 4 * t
>> > lead[lat.neighbors()] = -t
>> > sys.attach_lead(lead)
>> > sys.attach_lead(lead.reversed())
>> >
>> > return sys
>> >
>> > def main():
>> >
>> > sys = make_system()
>> >
>> > # Check that the system looks as intended.
>> > kwant.plot(sys)
>> >
>> > # Finalize the system.
>> > sys = sys.finalized()
>> >
>> > # Calculate ldos at a given energy
>> > well_depth = 0.55
>> > ldos = kwant.ldos(sys, energy=0.25, args=[-well_depth])
>> > kwant.plotter.map(sys, ldos, num_lead_cells=10)
>> >
>> > if __name__ == '__main__':
>> > main()
>> >
>>
>
>
--
Abbout Adel
/or
> copyright material. If you are not the intended recipient, please notify
> the sender immediately and delete this email and all copies from your
> system. Any unauthorized use, disclosure, reproduction, copying,
> distribution, or other form of unauthorized dissemination of the contents
> is expressly prohibited.
>
--
Abbout Adel
;
> Jan
>
> --
> Jan Behrends
> Max-Planck-Institut für Physik komplexer Systeme
> Nöthnitzer Straße 38, 01187 Dresden, Germany
> <https://maps.google.com/?q=N%C3%B6thnitzer+Stra%C3%9Fe+38,+01187+Dresden,+Germany&entry=gmail&source=g>
> E-Mail: j...@pks.mpg.de
>
>
--
Abbout Adel
bug? Thank you!
>
> Regards,
>
> Qiao Chen
>
>
> University of Antwerp
> Condensed Matter Theory
> Department of Physics
>
--
Abbout Adel
er.HoppingKind(*hopping3_MX)] = t3_MX
>
> def family_colors(site):
>
> return 0 if (site.family == M) else 1
>
> def hopping_lw(site1, site2):
>
> return 0.05 if site1.family == site2.family else 0.1
>
> def hopping_color(site1,site2):
>
> return 'g' if site1.family==site2.family else 'b'
>
> kwant.plot(sys,site_color=family_colors,site_lw=0.05,
> hop_lw=hopping_lw,hop_color=hopping_color,colorbar=False)
>
> return sys
>
>
>
>
>
> def main():
>
> lead = make_lead().finalized()
>
> kwant.plotter.bands(lead, show=False)
>
> pyplot.xlabel("momentum [(lattice constant)^-1]")
>
> pyplot.ylabel("energy [eV]")
>
> pyplot.show()
>
>
>
>
>
> # 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()
>
>
>
--
Abbout Adel
otice that. (This is true for tc <<1).
I hope this helps
Abbout Adel
On Tue, Jan 23, 2018 at 7:53 AM, SUDIN GANGULY
wrote:
> Dear Sir,
>
> Recently I was doing a problem on a 1D chain. The problem I faced is as
> follows.
>
> For a 1D chain, suppose I have taken 5 sites
ng')
>
>
>
>
> If anyone knows whether the problem is with the system or with the
> plotting it would be greatly appreciated.
>
> Regards
>
>
>
> --
> Dr. Eleni Chatzikyriakou
> Computational Physics lab
> Aristotle University of Thessaloniki
> elch...@auth.gr - tel:+30 2310 998109
>
>
--
Abbout Adel
ivate message) the other files and
I will do the test for you.
Hope this helps.
Adel
On Wed, Feb 7, 2018 at 1:29 PM, wrote:
> Hello Abbout Adel,
>
> The names are correct, I am just omitting in the post. I have changed the
> library call for wraparound, I still get an empty 3D space.
&g
leads to right lead
>
> pyplot.figure()
> pyplot.plot(energies, data)
> pyplot.xlabel("energy [t]")
> pyplot.ylabel("conductance [e^2/h]")
> pyplot.show()
> energies=[-3+i*0.02 for i in range(100)]
> plot_conductance(sys,energies)
>
--
Abbout Adel
reply. I have another query here. Can I add
> these two system together incorporating missing hopping elements?
>
--
Abbout Adel
rix.transmission(1,2) )
> #transmission from left 2 leads to right lead
>
> pyplot.figure()
> pyplot.plot(energies, data)
> pyplot.xlabel("energy [t]")
> pyplot.ylabel("conductance [e^2/h]")
> pyplot.show()
> energies=[-3+i*0.02 for i in range(100)]
> plot_conductance(sys,energies)
>
>
>
--
Abbout Adel
gt;
> return m*sz+0*sx
>
> else:
>
> return np.zeros([2,2])
>
>
>
>
>
> sys[lat.shape(disk,(0,0))]=onsite
>
> sys[lat.neighbors()]=-s0*2/3
>
> sys[A.neighbors()]=hopp
>
> sys[B.neighbors()]=hopp2
>
>
>
> lead0=kwant.Builder(kwant.TranslationalSymmetry((-a,0)))
>
> lead0[lat.shape(edge,(0,0))]=onsite
>
> lead0[lat.neighbors()]=-s0*2/3
>
> lead0[A.neighbors()]=hopp
>
> lead0[B.neighbors()]=hopp2
>
> sys.attach_lead(lead0)
>
> sys.attach_lead(lead0.reversed())
>
>
>
> kwant.plot(sys, fig_size=(30, 12))
>
>
>
> sys=sys.finalized()
>
>
>
> gf=kwant.greens_function(sys,0).submatrix(1,0)
>
> ##
>
--
Abbout Adel
A sublattice
> nnn_hoppings_B = (((1, 0), B, B), ((0, -1), B, B), ((-1, 1), B, B)) #
> Bonds within the B sublattice
> nnn_hoppings = nnn_hoppings_A + nnn_hoppings_B
>
> haldane_armchair = kwant.Builder(kwant.TranslationalSymmetry((0,
> 1*np.sqrt(3
>
> haldane_armchair[graphene.shape(ribbon_shape_armchair, (0, 0))] = onsite
> haldane_armchair[graphene.neighbors(1)] = nn_hopping
> haldane_armchair[[kwant.builder.HoppingKind(*hopping) for hopping in
> nnn_hoppings]] = nnn_hopping
>
> kwant.plot(haldane_armchair, site_color=site_color,
> hop_color=hopping_color, fig_size=(6, 9));
>
> kwant.plotter.bands(haldane_armchair.finalized(), args=[p], fig_size=(12,
> 8));
>
--
Abbout Adel
hoppings ? (it
> also doesn't work for random real nearest neighbors hopping terms)
>
> I will try to fix it by hand, by specifying the hopping terms between the
> cells, and see if it works.
>
> Best regards,
> Alexandre
>
> --
> *De: *&q
r.map(sys, d, cmap='gist_heat_r', colorbar=True)#, site_lw=0)
>
> ldos = kwant.ldos(sys, energy=0.5, params=params)
> print (ldos)
> kwant.plotter.plot(sys, ldos, num_lead_cells=2)
>
>
> Regards,
> priyanka
>
>
--
Abbout Adel
is
confusing!
I hope this helps.
Adel
[1]
https://mailman-mail5.webfaction.com/pipermail/kwant-discuss/2015-May/000355.html
Abbout Adel
On Wed, Jun 6, 2018 at 11:53 PM, Shivang Agarwal <
shivang.agar...@iitgn.ac.in> wrote:
> Hello authors,
>
> I am trying to perform an eigenchan
and had overlooked the
>> phase part. A noob mistake.
>>
>> Appreciate your help!
>>
>> Shivang
>>
>> On Thu, Jun 7, 2018 at 11:53 AM Abbout Adel
>> wrote:
>>
>>> Dear Shivang,
>>>
>>> To get the matrix Gamma you can do:
>&
ead always) for calculating the
> scattering matrix.
> Please, suggest me what is the code of voltage. (How to apply the voltage)
> Best,
> Rohit
>
--
Abbout Adel
of my hopping (e.g. case of graphene), but
> overall I'm not so sure of the units.
>
>
> Thank you again for your help.
>
>
> Kind regards,
>
>
> Marc
>
--
Abbout Adel
e), but
> overall I'm not so sure of the units.
>
>
> Thank you again for your help.
>
>
> Kind regards,
>
>
> Marc
>
--
Abbout Adel
y for calculating and plotting the full 2D
> band structure in the Brillouin zone.
>
> Can anyone give some useful solutions to my concern? Your help is much
> appreciated.
>
> Thank you and best regards,
> Kuangyia Lee
>
>
>
--
Abbout Adel
ied to separate the wave function based on the odd/even index, but it
> is not the right sequence.
>
> Thank you in advance.
>
> Regards,
> Yuhao
>
--
Abbout Adel
tonian_submatrix()
> evecs = la.eigh(ham)[1]
> psi=evecs[:, n]
>
> J_0 = kwant.operator.Current(syst)
> current=J_0(psi)
> print(len(current))
> kwant.plotter.current(syst, current, colorbar=False)
>
> wf = abs(psi)**2
> def site_size(i):
> return wf[i] / wf.max()
>
> kwant.plot(syst, site_size=site_size, site_color=(0, 0, 1, 0.3),
>hop_lw=0.1)
>
> def main():
> syst=make_system()
> plot_data(syst,900)
> syst2=make_system2()
> plot_data(syst2,900)
>
> if __name__ == '__main__':
> main()
>
>
--
Abbout Adel
reciated.
>
> Thanks and best regards,
> Shivang Agarwal
>
> --
> *Shivang Agarwal*
> Senior Undergraduate
> Coordinator - Academic Discussion Hours
> Discipline of Electrical Engineering
> IIT Gandhinagar
>
> Contact: +91-9869321451
>
--
Abbout Adel
s the Kwant simulation (in the case presented) uses a
> finite-difference discretization to render the problem discrete. If you
> decrease the 'a' parameter, you should see the discrepancy between the
> two result decrease.
>
>
> Happy Kwanting,
>
> Joe
>
--
Abbout Adel
.
>
> Can you give me some hints?
>
> Maybe my description is not clear, I attach the code in the e-mail to
> reproduce this question.
>
> Best wishes.
> Jinlong Zhang
> jlzhang1...@163.com
>
>
>
>
--
Abbout Adel
t it give
>> the same results with Datta’s transmission expression?
>> >
>>
>> Nice question!
>>
>> Looking at your results it seems that the energies at which new modes
>> open is shifted with respect to Datta's result.
>>
>> I believe that this is simply due to the fact that your discretization
>> is not fine enough. Datta's result is valid in the continuum limit,
>> whereas the Kwant simulation (in the case presented) uses a
>> finite-difference discretization to render the problem discrete. If you
>> decrease the 'a' parameter, you should see the discrepancy between the
>> two result decrease.
>>
>>
>> Happy Kwanting,
>>
>> Joe
>>
>
>
> --
> Abbout Adel
>
--
Abbout Adel
), lat(i, 1, k)] = M).
>
> Between the two options, nothing changes in the spectrum of the leads
> (fine !),
> but I does for the conductance of the junction.
>
> Can you help me ?
>
> Thank you very much
>
> L. L.
>
--
Abbout Adel
dagger}
> since I am starting with Kwant,
> I prefer to understand the low-level programming, first.
>
> Thank you very much again
>
> L.
>
>
> Il giorno mar 5 mar 2019 alle ore 10:20 Abbout Adel
> ha scritto:
> >
> > Dear Luca,
> >
> > Lookin
>
>
>
>
> Thanks in advance!
>
> --
> Hossein Karbaschi,
> PhD. in solid state physics.
>
--
Abbout Adel
ow to fix this seemly simple problem.
>
> Thank you very much for your help in advance.
>
> Hanning Chen, Ph.D.
> Assistant Professor
> Department of Chemistry
> George Washington University
> Washington, DC 20052
> http://www.chenlagbwu.net
>
>
>
>
>
--
Abbout Adel
Sgjg2I__LoPlFLL0-jSFpUZDZe_NmpizjAUd5aDVWfJ1pWtaEWkmo95Kor8QVS>
> no
> longer hermite ?
>
> --
> Jinlong Zhang
> jlzh...@163.com
>
>
>
>
--
Abbout Adel
a_0
>
>
> right_lead[lat(i, 1, k), lat(i, 0, k)] = -t*sigma_0
>
>
> # I close hopping in x-direction, connecting W-1 and 0
> for k in range(W):
> right_lead[lat(0, 0, k), lat(W-1, 0, k)] = -t*sigma_0
>
> # I close hopping in z-direction, connecting W-1
> for i in range(W):
> right_lead[lat(i, 0, 0), lat(i, 0, W-1)] = -t*sigma_0
>
>
> syst.attach_lead(right_lead)
> left_lead = right_lead.reversed()
> syst.attach_lead(left_lead)
>
--
Abbout Adel
gt; your archive. But when I have tried to execute it didn't work.
>
>
--
Abbout Adel
n main
> Ga = conj((Gr).T) #a for advanced
> NameError: name 'conj' is not defined
>
> Best,
> Sayan
>
>
> --
> *From:* Abbout Adel
> *Sent:* Monday, April 15, 2019 1:27:01 AM
> *To:* SAYAN MONDAL; kwant
matrix(sparse=False)
> print(np.matrix(sparse_mat))
> evs = scipy.sparse.linalg.eigs(sparse_mat,10)[0]
> print(evs.real)
>
> #conductance calculation through transmission matrix
> energies = []
> transmission = []
>
> for ie in range(100):
> energy = ie * 0.01
> smatrix = kwant.smatrix(device, energy)
> energies.append(energy)
> transmission.append(smatrix.transmission(1,0))
>
> plt.figure()
> plt.plot(energies,transmission)
> plt.xlabel("energy")
> plt.ylabel("conductance")
> plt.show()
>
>
>
--
Abbout Adel
ere is a hopping
> integral missing in the left lead.
>
>
>
> Otherwise, I writing the same lead which I don’t replace *lead1* with*
> sys* in the symmetric direction, there is no error here.
>
>
>
> Please help me solve this problem,Thanks!
>
>
>
> In the attachment, I will attach my program.
>
>
>
> Sincerely yours,
>
> F.X. Yan
>
>
>
> 发送自 Windows 10 版邮件 <https://go.microsoft.com/fwlink/?LinkId=550986>应用
>
>
>
>
>
--
Abbout Adel
ind I had given is right or wrong. Is there
> any way to visualize those hoppings in the 3d plot (as we can see in the 2d
> plot).
>
>
> Ah, that's a good point. Perhaps you could make the 2 lattices in 2D but
> put an offset in the x-y positions of the sites in one of the layers of the
> bilayer. This way you can still visualize the hoppings using kwant.plot and
> the sites occupy distinct positions in space. Because we are limited by
> matplotlib's poor 3D rendering we cannot display the hoppings in 3D plots.
>
>
> Happy Kwanting,
>
>
> Joe
>
--
Abbout Adel
g above codes the time costed increases as periodic_x or L_y
> become large.
>
>
> Best regards
> Zhan Cao
> Southern University of Science and Technology of China
>
>
>
>
--
Abbout Adel
gt; Hence, there’s something wrong with the calculation. I don’t know how to
> solve the warning.
>
>
>
> Please help me solve my bewilderment , Thanks!
>
>
>
> Best regard,
>
>
>
> Yan
>
>
--
Abbout Adel
0 , 0.0 , 0.0)] = -4.0
> syst[basis[0](0.0 , 0.0 , 0.0) , basis[2](8.0 , 0.0 , 0.0)] = -4.0
> syst[basis[0](0.0 , 0.0 , 0.0) , basis[3](8.0 , 0.0 , 0.0)] = -4.0
> syst[basis[0](0.0 , 0.0 , 0.0) , basis[4](8.0 , 0.0 , 0.0)] = -4.0
>
> kwant.plot(syst)
>
> syst = builder.finalized()
>
> sparse_mat = syst.hamiltonian_submatrix(sparse=False)
> print(np.matrix(sparse_mat))
> evs = scipy.sparse.linalg.eigs(sparse_mat,3)[0]
> print(evs.real)
>
> ===
>
>
>
--
Abbout Adel
Please let us know when you find a solution. We are particularly
> interested if you find some problem with Kwant (or its documentation).
>
> Owocnego Kwantowania!
>
> Krzysiek
>
--
Abbout Adel
>
>
>
>
>
>
>
> Naveen
> Department of Physics & Astrophysics
> University of Delhi
> New Delhi-110007
>
--
Abbout Adel
stems it shows an *ValueError: Only 2D systems can be plotted this
>> > way.* Please suggest me if there is a way to plot probability density
>> > for 3D system having only an orbital degree of freedom per site.
>>
>> Kwant's plotting submodule is based on matplotlib, whose 3D features are
>> very rudimentary and slow. And anyway, what kind of plot do you have in
>> mind? There are many different ways to plot 3D densities, appropriate
>> for different situations/data.
>>
>> For serious 3D plotting, I suggest using a separate library. For
>> example, you could give MayaVi a try.
>>
>
>
> --
>
>
> With Best Regards
> NAVEEN YADAV
> Ph.D Research Scholar
> Deptt. Of Physics & Astrophysics
> University Of Delhi.
>
--
Abbout Adel
e new window,
> in case that matters).
>
> Thanks
> Antonio
>
--
Abbout Adel
der if it is
> possible to get the correct DOS with limited energy window.
>
> Best,
> Antonio
>
> Em dom, 16 de jun de 2019 às 05:11, Abbout Adel
> escreveu:
>
>> Dear Antonio,
>>
>> Without an example, your problem may be not very clear. Could you pro
t;
> Also, I'm not sure that if I want to calculate the current at a certain
> energy (like "-1" above),
> do I have to calculate the current at all the wavefunction (like for all p
> of wf(0)[p])
> or I have to calculate the current only at the wavefunction with "negivate
> velocity"?
>
> Thanks in advance for your help.
> Hang Zang
>
--
Abbout Adel
##
Hang Zang
>
> On Sun, Jun 23, 2019 at 8:22 AM Abbout Adel wrote:
>
>> Dear Zang,
>>
>> If you do not specify the region where you want to calculate the current,
>> kwant will do that for all the hoppings in your system. In your case, I
>> guess that
quite clear with the unit of the output current.
>
> Besides, is the current calculated by the second method should be equal to
> the first method?
>
> Thanks in advance for your help.
> Hang Zang
>
--
Abbout Adel
2, 1, projection='3d')
> ax.plot_trisurf(x, y, z, triangles=tri.triangles)
> ax.set_zlim(-1, 1)
>
> plt.show()
>
>
>
--
Abbout Adel
hich I computed the
> local charge densities "ch_densities", which is basically a vector of
> length=len(sys_f.sites).
> >
> > For complexity reason, I'd like to feed a slice of sys_f to the
> interpolate_density() as:
> >
> > >> kwant.plotter.interpolate_density(syst=sys_p, density=ch_densities_p)
> >
> > where sys_p is a slice of sys_f and ch_densities_p is the corresponding
> density vector.
> > Could you please let me know how to do it?
> >
> > Best regards,
> > Hadi
>
--
Abbout Adel
ams=dict(B=B), sparse=True)ev, evec =
> sla.eigsh(ham_mat.tocsc(), k=20, sigma=0)energies.append(ev)
> #print(energies)plt.figure()plt.plot(Bfields, energies)
> plt.xlabel("magnetic field [${10^-3 h/e}$]")plt.ylabel("energy [t]")
> plt.ylim(0, 0.11)plt.showdef main():syst = make_system()
> analyze_system()main()*
>
>
>
>
> --
>
>
> With Best Regards
> NAVEEN YADAV
> Ph.D Research Scholar
> Deptt. Of Physics & Astrophysics
> University Of Delhi.
>
--
Abbout Adel
#print (energies)plt.figure()plt.plot(Bfields, energies)
> plt.xlabel("magnetic field [${10^-3 h/e}$]")plt.ylabel("energy [t]")
> plt.ylim(0, 0.11)plt.show()def main():syst = make_system()
> analyze_system(syst, [B * 0.2 for B in range(101)])main(
e
>> def circle(pos): rsq = pos[0] ** 2 + pos[1] ** 2
>> depends on pos
>>
>> Because when creating a shape in realspace you typically only care about
>> the position, whereas your onsite matrix elements could potentially depend
>> on other things (e.g. the lattice that the site is from)
>>
>>
>> Happy Kwanting,
>>
>>
>> Joe
>>
>
--
Abbout Adel
in_block” in “lead=kwant.Builder()”
>
>
>
> The program can not work, and prompt error:
>
>
>
> IndexError: index 2 is out of bounds for axis 0 with size 2
>
>
>
> Please help me.
>
>
>
> Thank you,
>
>
>
> Kind regards,
>
> X.F.Yan
>
>
>
>
>
>
>
--
Abbout Adel
thon script with this email.
>
> Does anyone know the reason behind the discrepancy between the two
> methods?I would greatly appreciate any comments/suggestions on how we can
> resolve this error?
>
> Thanks!
>
>
>
>
--
Abbout Adel
“or” use “and”).
>
>
> I would really appreciate if we could resolve this discrepancy. I look
> forward to any suggestions.
>
> Thanks for your time!
>
> On Sun, Sep 15, 2019 at 7:27 AM Abbout Adel wrote:
>
>> Dear Amrit,
>>
>> You wrote:
>> "
PM Ali Asgharpour
wrote:
> Hello,
>
> Would you please let me know how I can add nn and nnn hoppings for
> random sites (not all) in graphene?
>
> Best regards,
>
> Ali
>
--
Abbout Adel
ad(lead.reversed(),add_cells=3)
>>>
>>> ax=kwant.plot(syst);
>>>
>>> Best wishes,
>>> Nafise
>>>
>>> On Sat, Oct 5, 2019 at 12:57 PM Joseph Weston
>>> wrote:
>>>
>>>> Hi Nafise
>>>>
>>>>
>>>> I need to make a periodic lattice with hole. In fact I should make holes
>>>> on the scattering region and also on the leads. Although I can make this
>>>> kind of lattice by kwant, I have problem about the distances between
>>>> holes. I want to make a periodic holes on the nanoribbon but the distance
>>>> between holes in the scattering region is different from the distance
>>>> between holes in the other regions. Would you please let me know How Can I
>>>> make a same distance between holes? Should I work on the translational
>>>> symmetry in the leads?
>>>>
>>>>
>>>> Because the leads need to be translationally invariant if you want a
>>>> very large distance between defects then your unit cell in the leads needs
>>>> to be correspondingly large.
>>>>
>>>> If you post a code example of what your problem is specifically we may
>>>> be able to help more.
>>>>
>>>>
>>>> Happy Kwanting,
>>>>
>>>> Joe
>>>>
>>>>
>>>> P.S. sorry for the double reply; I forgot to send to the mailing list
>>>> also
>>>>
>>>>
--
Abbout Adel
?Thanks in advance. The definition of incident angle is shown in the
> attached Fig.1， the band structure for my bulk system is shown in attached
> Fig.2 and the Tranmission vs ky is shown in Fig.3 (I do not know how the
> set the values for ky).
> Regards,
> Hosein Khani
>
>
>
--
Abbout Adel
and
> lead but the results are not same.
>
> Would you please help me what is a problem. Would you please let me know
> if symmetry vector (sym = kwant.TranslationalSymmetry(latt.vec((-1,2
>
> used is ok?
>
> Best wishes,
>
> Sajad
>
--
Abbout Adel
>>
>>>>>> lead[[kwant.builder.HoppingKind((0,0),a,b)]] =t
>>>>>>
>>>>>> lead[[kwant.builder.HoppingKind((0,1),a,b)]] =t
>>>>>>
>>>>>> lead[[kwant.builder.HoppingKind((-1,1),a,b)]] =t
>>>>>>
ransmission
def T(E):
return arccos(-1+abs(E/2))
Energies=linspace(-2,2,200)
pyplot.plot(Energies,T(Energies))
pyplot.show()
###
On Sun, Oct 27, 2019 at 2:42 PM Abbout Adel wrote:
>
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