Re: [Kwant] Four leads or six leads in hall bar-How to use " add_site_family" exactly in Kwant

Dear Bill, > This is David's question.Link is > https://mailman-mail5.webfaction.com/pipermail/kwant-discuss/2014-October/000169.html > . In a response to that question Michael Wimmer posted example code [1]

Re: [Kwant] Four leads or six leads in hall bar-How to use " add_site_family" exactly in Kwant

Hi Bill, > Dear Joe    >     "add_site_family" did work in graphene zigzag nanoribbon.When I > use "add_site_family",the central scattering region would not enlarge > after connected with leads in zigzag nanoribbon.But when I use it in > graphene armchair nanoribbon,the central scattering region

Re: [Kwant] Visualize current through a 2D cut for a 3D system

Hi, > > Is it also possible to help me with this function to match first > nearest neighbor sites for the where argument in kwant.operator.Current: > > def first_neighbors(site_to, site_from): > for i in site_from.family.neighbors(1): >   if(??): >     return True >   else >   

Re: [Kwant] Visualize current through a 2D cut for a 3D system

Hi again, > Hello Joseph, > > One problem that I see is that I can only get neighbors() from > Builders and lattices (using site.family). > > Using something like this: > > def first_neighbors(to_site, from_site): >   return to_site in from_site.family.neighbors(1) > > is a good idea, but am I rea

Re: [Kwant] Issue with a semi-infinite ribbon

Hi, > Hello, > > I encountered an issue when dealing with a semi-infinite ribbon: when > defining a 1D translationnal invariance, I end up with a unit cell > with unwanted and unexpected additionnal degrees of freedom. I ran your script an indeed the plotter only plots 24 sites, and when I inspe

Re: [Kwant] Issue with a semi-infinite ribbon

Hi again, > > But in my case, the 'true' hamiltonian I need to consider is the one > given by 'hamiltonian_submatrix()', and not 'cell_hamiltonian()' which > is for an isolated cell ? > > Then we agree that my states close to zero energy aren't fake ones ? > In that case I don't understand how the

Re: [Kwant] seeking help

Hi, > Dear Sir, >    >      I want to model a bi2se3 nanowire in kwant to investigate the > transport properties. >     > Please help me in this regard. Your question may have several interpretations: 1. How do I make a tight-binding model for Bi2Se3 that includes all relevant physics for my ap

Re: [Kwant] Hamiltonian not hermician for an infinite wire with random complex hopping

Hi, > Hi again, > > Sorry if I am spamming you a bit, but I have new informations about my > issue : > - my cell hamiltonian is not hermician, but my full hamiltonian is > hermician (tested with 'np.allclose(ham, ham.conjugate().transpose())' > for both hamiltonians) > - if I put a random magnitu

Re: [Kwant] Hamiltonian not hermician for an infinite wire with random complex hopping

On 05/22/2018 03:06 PM, alexandre.berna...@u-psud.fr wrote: > Then, thanks to both of you, I think it is safe to say that the case > is solved : > > the hermicity of the hamiltonian is 'ensured' by Kwant by _recalling > the same function_ (and taking the complex conjugate) for i--->j and > for j--

Re: [Kwant] Changing the potential in a continuum Hamiltonian

Hi, You can do what you want by declaring extra parameters to the 'V' function when you make your Hamiltonian:     H = 'k_x**2 + k_y**2 + V(x, y, Vgate)'     template = kwant.continuum.discretize(H)     syst = kwant.Builder()     syst.fill(template, ...)       ...     def gate(x, y, Vgate):

Re: [Kwant] Defining orbitals in a 3D structure with 3 basis atoms.

Hi all, Sergio, if you want to create a Polyatomic lattice you have to pass all the basis vectors and orbital numbers in a single call to 'kwant.lattice.general', otherwise there's no way Kwant can know that you want the 3 sublattices to be considered as a single Polyatomic lattice!     prim_vec

Re: [Kwant] Coupling Matrix between Lead and Conductor

Hi, > > I have a matrix giving me the complex wave function at each site. How > do I know which mode (m/n) do the amplitudes correspond to? Where did you get this matrix from? Is this the wavefunction of a mode in a lead, from 'kwant.modes', or of a scattering wavefunction, from 'kwant.wave_func

Re: [Kwant] Josephson current in a lattice between two superconductors

HI Ville, > I'm trying to use Kwant to investigate behavior of a lattice between > two superconductors, namely trying to figure out the Josephson > current. The task is basically to diagonalize the related > Bogoliubov-de Gennes Hamiltonian and use the eigenvectors and > eigenvalues to calculate

Re: [Kwant] Onsite and hopping values in QHE

HI, > > I am trying to reproduce the QHE bar device calculations > > http://nbviewer.jupyter.org/github/topocm/topocm_content/blob/master/w3_pump_QHE/Laughlinargument.ipynb > > > However, I am having difficulty with the onsite and hopping values as > I am using TBModels > > https://github.com/Z2P

Re: [Kwant] Defining orbitals in a 3D structure with 3 basis atoms.

Hi again, > > But im still confused about some definitions > > 1) Alexandre, thank you for you suggestions, but honestly Im not > pretty sure how to define a "superatom" that reproduces the structure > im working on. How should i define the sites for each atom in the lattice? He means that instea

Re: [Kwant] Band Structure in an Electric Field (Lead vs System)

Hi, > I want to plot the band structure for my system, i.e. a quantum dot. I > am still confused as to what code I need to write to plot that, or > whether sys.leads[0] is actually correct for what I need. Calculating a band structure for a quantum dot is not mathematically well-defined. A quant

Re: [Kwant] Band Structure in an Electric Field (Lead vs System)

> Thank you Joesph. That clarifies my understanding of band structure > and translational symmetry. > > My end goal is to see changes in the band structure as the electric > field is varied. For an external magnetic field (wherein I modify the > hopping parameter only) the band structure changes

Re: [Kwant] Onsite and hopping values in QHE

Hi > sym = kwant.TranslationalSymmetry( >     lattice.vec((1, 0, 0)), >     lattice.vec((0, 1, 0)), > lattice.vec((0, 0, 1)) > ) > > [] > > #Hall bar > def onsite(site, B): >   (x, y, z) = site.pos >   return stored_model[site] > > def hopping_Ax(site1, site2, B): >   x1, y1, z1 = sit

Re: [Kwant] Calculating valley polarized conductances using Kwant

Hi Kevin, Thanks for the well-posed and focused question! > I would like to calculate the valley polarized conductance for a graphene > nanoribbon with 2 leads (let’s say in the x-direction). My current approach > is this: > > 1) Get the S-matrix for a certain energy > 2) Find the indices of th

Re: [Kwant] regarding error message

Dear Shyam, > > File "C:\Users\Shyam Lochan Bora\Desktop\new 1.py", line 5, in >     from wraparound import wraparound > ModuleNotFoundError: No module named 'wraparound' > > Help me in this regard 'wraparound' is now included with Kwant, as of version 1.3. You can change the line:     from wra

Re: [Kwant] Voltage

Hi Rohit, > Is this code correct for the voltage applied in the 3rd lead? I briefly looked at your code and you seem to be calculating the scattering matrix for a stadium with 3 leads attached, except two of the leads are 1 site wide and overlap. I am almost 100% sure this is not what you inten

Re: [Kwant] About MoS2 ribbon

Hi, > When I use kwant to calculate the conductance for MoS2 ribbon, zigzag > edge is right, however, for armchair edge ribbon, errors occure as > follows, > > LinAlgError: QZ iteration failed to converge in zgges. > > I am very comfused about this. Thanks! Thanks for the report, other people h

Re: [Kwant] Modify the onsite energy of the majorana fermions (example D6 in the paper)

Hi, > > def onsite(site, p): > x, y = site.pos > E = 0.15# the magnitude of electrical field in y direction > return tau_z * (p.mu - 2 * p.t) + sigma_z * p.B + tau_x * p.Delta + E* y*  > s_0 > > s_0 = numpy.identity(2). However, the program crashed to  > UserCodeError: Error occurr

Re: [Kwant] Attaching 3D Leads to a 3D System

Hi, > > I am trying to attach a 3D lead to a 3D system that I have built, but > am facing troubles in the same. I am aware of another thread > (https://mailman-mail5.webfaction.com/pipermail/kwant-discuss/2014-May/000125.html) > highlighting my question, but having gone through that thread I was

Re: [Kwant] issues with Current calculation

Hi, >   I am trying new Kwant 1.3 features on a very simple example of > graphene monolayer, and, apart from a standard well-working code I add: > > for x in sys.sites(): x.family.norbs=1 for x in leadxp.sites(): > x.family.norbs=1 for x in leadxm.sites(): x.family.norbs=1 (to avoid > norbs not de

Re: [Kwant] issues with Current calculation

ice to have this in tutorials. > In my case,  I still get a error >  Exception "unhandled kwant._common.UserCodeError" > Error occurred in user-supplied value function "hopping". > > Although, my hoppings are pretty innocent  and conductance calculation > works fin

Re: [Kwant] issues with Current calculation

Good morning, > Hi Joe,  Thank you, now it works! Nice! >   But I am a bit confused about the physical meaning of the current, > created by modes in lead n.   How to plot the real current between the > two leads?  Imagine,  as the simplest case, that my geometry is > inversion-symmetric,  so th

Re: [Kwant] issues with Current calculation

Hi Sergey, > 1)  This code gives a strange error: > > The debugged program raised the exception unhandled TypeError > "streamplot() got an unexpected keyword argument 'start_points'" > File: > /home/sergey/.local/lib/python3.6/site-packages/kwant/plotter.py, > Line: 2164 > > which is strange sinc

Re: [Kwant] issues with Current calculation

Hi Sergey, > Also, I found that current asymmetry was indeed there and it was > caused by numerical errors: the precision of the current calculation > is higher near the lead for which it is calculated, while the error > may grow significant near other lead(s).  In my case,  at some > energies it

Re: [Kwant] Units of density

Hi, > I've found in other threads in the mailing list that the units of > current is for example (unit of charge)/(hbar/unit of energy) > (https://www.mail-archive.com/kwant-discuss@kwant-project.org/msg01100.html). > Also, the local density of states has units of energy/volume > (https://www.mai

Re: [Kwant] Extract wavefunction for one lattice

Hi Yuhao > In the system I use two lattices to represent spin up and down. > > lat_u = kwant.lattice.honeycomb(a=1, name='up')  > lat_d = kwant.lattice.honeycomb(a=1, name='down') > > When I obtain the scattering wave functions from > wf=kwant.wave_function(sys, en),  > it contains the value for

Re: [Kwant] The right way to build up a system?

Hi Guangze, > I am trying to plot the density and current density of a chiral edge > state in a 2D quantum Hall system. I tried to build up the system in > two ways: > 1. define two sublattices, > 2. define one lattice, use matrix form for the on-site potential and > hoppings > I expected that t

Re: [Kwant] Fixing min and max values of colormap using kwant.plot

Hi, > Thank you for the quick response. When I try /kwant.plotter.map(sys, > value, vmin=0, vmax=2) /I get the following error: > ValueError: Only 2D systems can be plotted this way. > My system is a 3D system. I would be glad if you could help me out in > this regard. > As the error message say

Re: [Kwant] Error visualizing the zigzag graphene lattice using kwant.plot() in tutorial

Hi Srilok, > > I am very new to kwant and I am still learning to use the code. So > my apologizes for any trivial questions. > > I working on the tutorial notebooks I found in the here > (https://kwant-project.org/mm16). In the tutorial > 3.4.graphene_qshe.ipynb I am trying to

Re: [Kwant] Error visualizing the zigzag graphene lattice using kwant.plot() in tutorial

Just to respond to Anton: > Right now plotting of detached finalized leads isn't supported and is > tracked in the issue > https://gitlab.kwant-project.org/kwant/kwant/issues/18 They're not plotting a finalized system: >>> zigzag_ribbon = kwant.Builder(kwant.TranslationalSymmetry([1, 0])) >>> #

Re: [Kwant] Error visualizing the zigzag graphene lattice using kwant.plot() in tutorial

Hi everyone, > This is very strange; when I download the notebook and run it I indeed > see the error that you reported, however when I try to run the > following minimal example it succeeds: > > >> import numpy as np >> import matplotlib.pyplot >> import kwant >> >> graphene = kwant.lattice.gen

Re: [Kwant] How to plot the lead band of non hermitian Hamiltonian with Kwant

Hi, > In the kwant, I want to plot the lead band of non hermitian > Hamiltonian and I just add some imaginary terms to the onsite > term.However, the error "The cell Hamiltonian is not Hermitian" will > appear. How can I solve the problem?  >              I am looking forward for your reply and I

[Kwant] Change conductance step units

The message below was originall from Sergio Castillo. For some reason neither I nor several other Kwant developers received this message from the mailing list, so I'm reposting it here. > Hello everyone, I would appreciate any suggestion you could give me to > solve this: > > Im trying to plot th

Re: [Kwant] semicon

Hi Ali, > I want to find conductance of a heterostructure using semicon library. > When I just use coords='z', everything is OK. But, when I want to > change it to two dimensions like 'xz', I encounter an error. Would you > please tell me how I can fix it? I hope it is not just a > simple mistake

Re: [Kwant] semicon

Thanks for the information! > Thank you for your quick response. I am using kwant 1.3.3 version and > semicon 0.1.0 version. I think the error is related to calling > parameters function which are stored as a tuple. By the way, this is > the error I encountered: > > TypeError

Re: [Kwant] Drawing edge states in zGNR (using tutorial 2.8)

Hi Elmo, > Is there a simple example out there showing how I can build a zigzag > nanoribbon, just using nearest neighbour hopping, and extract the > wavefunction and draw said nanoribbon exactly like the figure at the > end of the 2D part of that tutorial. Can't you just take the example from

Re: [Kwant] complex conjugate operator

Hi 张金龙, Thanks for posting to the mailing list. >  Recently, I want to calculate the conductance of Superconductor > junction. > > Let me take the p+ip topological superconductor as the example. Its > Hamiltonian is like > with \sigma, \tau is the Pauli matrix for spin and particle-hole. > > It h

Re: [Kwant] Install Kwant on Win 10

Hi Zhanzhi, It seems like you don't have Python installed. You have to first install Python on your machine in order to use Kwant. Happy Kwanting, Joe On 12/29/18 5:47 PM, Zhanzhi wrote: > > Hi, > >   > > I am trying to install Kwant on a Win 10 PC. I followed the steps > https://kwant-projec

Re: [Kwant] Install Kwant on Win 10

Hi, > > Thanks for reply. Actually I installed python 3.6 and can do python > programming on my PC. > > image.png > > Do you have any idea about this? > Probably Python is not in your PATH. Did you exactly follow the instructions on the Kwant website? It seems that step 4 here:https://kwant-pr

Re: [Kwant] Datta’s ballistic transport formalism vs KWANT

Hi Ran, > I tried to compare KWANT’s results for transmission with Datta’s > ballistic transport formalism where total transmission is written as > > Ttot=T(E)M(E) > > Here Datta takes T(E)=1 for ballistic transport (please see: J. Appl. > Phys. 105, 034506, 2009) and M(E) is the number of modes i

Re: [Kwant] Problem with semimetals

Hi Luca, > I have tried to implement a couple of examples of semimetals with Kwant, > where the lattices (scattering regions) are taken square or cubic, > and the leads attached on entire faces of the lattices. > I assumed both open and periodic (in the directions orthogonal to the leads) > boun

Re: [Kwant] Berry phase of a system periodic in 1 direction

Hi, On 2/15/19 6:42 PM, Srilok Srinivasan wrote: > Dear Kwant users and developers, > > Is there a way to calculate the integral(< u_nk | d_k(u_nk)>dk)  > across the 1D BZ of a system periodic in one direction. Here u_nk is > the periodic part of the Bloch wave function corresponding to band n. >

Re: [Kwant] Updating Kwant

Hi Marc, > I want to implement the latest development of Kwant since I want to > try to calculate Kubo conductivities with the KPM method (as it > appears in the development version of the documentation). I tried to > use Conda to update the packages (conda install -c kwant kwant) but I > still ge

Re: [Kwant] Transmission matrix and momenta

Hi Luca > Dear all, > > I am trying to obtain the coefficients of > the transmission matrix (fine, so far.) > and to related them to the modes of the leads. This is covered in the FAQ [1]. You can use 'lead.modes()' to get the mode wavefunctions, and the scattering matrix entries are ordered

Re: [Kwant] Attaching single leads - quantum transport

Hi Nuwan, > I am new to Kwant and I am trying to attach a single infinite lead > from both sides for the case of quantum transmission through a single > impurity site to get the maximum transmission probability.  > > Also, how can we develop the tutorial example of "Transport through a > Quantum

Re: [Kwant] kwant installation via conda in windows 10

Hi Xiaoyan, > In the newest release of kwant (Ver 1.4.0), it has been announced that > windows installation can be done via Conda. However, there is no guide > about this in the “installation section” page. It seems that > “installation section” is old and not matching the new release. Any > step-

[Kwant] Kwant tutorial notebook

Dear all, I recently gave a tutorial at the University of Maryland about quantum transport and more specifically using Kwant in that context. The tutorial also contained a relatively in-depth discussion of the linear algebra that Kwant performs internally. Because this is of general interest to

Re: [Kwant] discretised Hamiltonian

Hi, > Dear Developer, >          The discretised Hamiltonan shown in Kwant release version > 1.4.0 in Article# 2.2.1 is not being understood when I try to attach > significance of "ket" and "bra" state to the symbols e.g.   │i+1,j> > and |i+1,j>. Such operators can be used as a basis for writing

Re: [Kwant] [KWANT] Diagonalization of hamiltonian

Hi, > I want to diagonalize the model hamiltonian containing sine and cosine > functions with momentum operators as their argument. > > H(k) = tx*σx* sin kx + ty*σy*sin ky + mk*σz + λ*σ0 *sin kz, > > mk = tz(cos β − cos kz) + t'(2 − cos kx − cos ky) If you just want to diagonalize a 2x2 H(k) the

Re: [Kwant] Regarding the NNN term in bilayer graphene across the layer

Hi, >  I am trying to put next nearest neighbor hopping terms across the > layer in bilayer graphene. In that case, how can I get those hopping > kind directions for the NNN hopping for the interlayer or can I use > sys [ lat.neighbor(3)] or sys[ lat.neighbor(4)]? > The answer will surely depend

Re: [Kwant] Regarding the NNN term in bilayer graphene across the layer

>   I have constructed the lattice with third dimension > Z0 using kwant.lattice.general. As the system is giving a 3d plot, I > am unable to visualize the hopping between nearest neighbors and so on > which make me confused whether the hopping kind I had given is right > or wrong.

Re: [Kwant] [KWANT] Diagonalization of hamiltonian

Hi, > Dear Joe, > I just want to plot the Landau levels of the edge states without > taking into account the spin of particle for the thin slab with Wx =10 > and Wy = 50. Here Wx and Wy are the width of slab in x and y direction > and magnetic field is along x direction. And kz is a continuous >

Re: [Kwant] [KWANT] Diagonalization of hamiltonian

> > I have build the system(discretized in x and y direction). The actual > problem is that, " How to add magnetic field term(as given by the > auther l_m = 4.5) to this system?" These bands are in presence of > magnetic field. Well you'll have to look in the paper to answer that question; you'r

Re: [Kwant] Peierls phase substitution on Tight-Binding Hamiltonian

Hi, On 5/5/19 1:08 PM, Naveen Yadav wrote: > Dear KWANT developers, > > I have an Hamiltonian > *H(k) = tx*σx* sin kx + ty*σy*sin ky + mk*σz + λ*σ0 *sin kz,* > * > * > *mk = tz(cos β − cos kz) + t'(2 − cos kx − cos ky)* > ** > > I am trying to introduce magnetic field in *x-direction* for a gauge

Re: [Kwant] Peierls phase substitution on Tight-Binding Hamiltonian

> > Then as you said I have to multiply the hopping in z direction by > exp(2 * pi * 1j *  B * a* y). But how can I build a 3D system from > here. I know that 2D systems can be written as *lat = > kwant.lattice.square(a), *but I don't know how should I proceed to > bulid a lattice in 3D using the

Re: [Kwant] STM tip

> I want to use KPM to calculate LDOS vs. energy for a given position. > Apparently, I can do it using 'where' in kwant.operator.Density, but > the input must be a crystal position. I wonder if there is any form to > find the closest crystal position for a given position vector that > does not nec

Re: [Kwant] Peierls phase substitution on Tight-Binding Hamiltonian

> Dear Joseph, > > As per your instructions I have build the system, but the code is not > giving the desired result. > Here is the code please have a look on it. 'y' should be the y position of the sites of the hopping, not an input parameter to the system construction:     def hoppingz(site0,

Re: [Kwant] Peierls phase substitution on Tight-Binding Hamiltonian

> That is okay, but still something wrong. > Well I am afraid that the only way to proceed is for you to look closely at what you have implemented, and what is written in the paper and see where there is a discrepancy. You could also ask the authors for the code that they used to produce the imag

Re: [Kwant] Peierls phase substitution on Tight-Binding Hamiltonian

> And also, when I am plotting the spectrum in varing magnetic field > with the hamiltonian as a sparse matrix. I am getting an value error. > *ValueError: x and y must have same first dimension, but have shapes > (100,) and (1, 15) * > I don't know what does it mean? > > *def plot_spectrum(syst,

Re: [Kwant] Error with params SimpleNamespace

Hi, > I’ve been running into the same error message over and over when > trying to pass a SimpleNamespace to the function > hamiltonian_submatrix(). I am using Python 3.7.3 and Kwant 1.4.1. > Could it be that this is due to a too recent Python version? > > >   > > pars = SimpleNamespace(t=1, mu=-

Re: [Kwant] A question about the representation of the wavefunction

Hi Adel, I read through this thread and I'm still not really sure what is being proposed. In the first email in the thread it seems as if you are proposing a wrapper for wavefunctions so that they can be indexed by site. It seems that you want to be able to write:    psi(i).dagger() * syst.hamil

Re: [Kwant] Staggered Sublattice Potential

Hi, > Respected Sir, > >                      I want to include the staggered sublattice > potential in Kwant. The problem is, it is an onsite term which takes > positive and negative values to two different sublattices of Graphene. > how will I include this onsite potential? > I would recommend

Re: [Kwant] honycomb lattice with hole

Hi, > I’m new in kwant and I want to use this package to calculate transport > properties of some graphene-liked materials with multi orbital per atom. In > order to define hopping in the form of matrix, we need to determine the > relative coordinate of neighbor sites. If we build the system u

Re: [Kwant] honycomb lattice with hole

> sym = kwant.TranslationalSymmetry(latt.vec((-1,0))) >      > sym.add_site_family(latt.sublattices[0], other_vectors=[(-1, 2)]) > sym.add_site_family(latt.sublattices[1], other_vectors=[(-1, 2)]) > lead = kwant.Builder(sym) >   >   > > > Making a hole on the scatter reign is ok. I did the same

Re: [Kwant] Bound states calculation

Hi Oleksii, > I came across the algorithm described in > https://scipost.org/SciPostPhys.4.5.026, and I think I would benefit a > lot from it. I am wondering whether it is implemented in the new kwant > 1.4 library, or is there an implementation publicly available somewhere? The bound state algor

Re: [Kwant] Questions about conductance

HI Dominic, > > I am using Kwant to stimulate 2D nanowire (square lattice) with two > barriers (quite similar to NS junction described in Section 2.6 in the > tutorial but topological superconductor is sandwiched between two > barriers) and I am measuring the conductance across it using > "smatrix

Re: [Kwant] 3D annulus cylinder

Hi, > Dear KWANT developers, > > I want to generate a 3D annulus cylinder with hopping in all the three > directions(periodic in x-direction) like the following figure. Please > suggest me the way to generate such type of geometry. If possible then > provide an example code for that for better un

Re: [Kwant] 3D annulus cylinder

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 yo

Re: [Kwant] Difference between hop[0].tag and hop[1].tag

Hello, > > What is the difference between   hop[0].tag   and hop[1].tag > hop[0].tag is the tag of the first site in the hopping and hop[1].tag is the tag of the second site in the hopping. > > My second question  > the onsite fuction for example: def onsite(site, V):return V > > why it depends

Re: [Kwant] Wavefunction for 2D NISIN

Hi, >   > I still don’t understand exactly how I can implement this. From what I > can understand you choose the energy not the eigenstate for the > density function. I am unclear what you mean here. In your code you do the following:     ham_mat = sys.hamiltonian_submatrix(sparse=True, param

Re: [Kwant] How to solve the Hamiltonian matrix with off-diagonal terms?

Hi, > We consider the values of the  conservation law based on the > off-diagonal term of Hamiltonian matrix, details are as follows: > >   > > H = tinyarray.array([[0, 0, 0, 1, 0, 0], > >     [0, 0, 0, 0, 1, 0], > >     [0, 0, 0, 0, 0, 1], >

Re: [Kwant] help conda

Hi, > Dear Sir, > I have a problem to install Kwant when download the Pre-built packages ( > Anaconda package ). That is to say I can't download the package. My > operating systems is Microsoft Windows. Can you help me. Please provide more information; what exact steps did you take when tryin

Re: [Kwant] question

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

Re: [Kwant] Josephson Junctions using tkwant

Hi Denise, > > Has anyone recently tried to simulate Josephson Junctions using tkwant? > I tried to follow the examples and tutorials, but several of them do > not work in the last tkwant version. Unfortunately tkwant does not presently have a maintainer, and no developer time has been allocated

Re: [Kwant] Josephson Junctions using tkwant

Hi again Denise, I'm just writing again to clarify something I wrote in my previous reply: > Unfortunately tkwant does not presently have a maintainer, and no > developer time has been allocated to it. This may change in the future, > but at this point we cannot provide any promises. tkwant was a

Re: [Kwant] Non-equilibrium Green's functions and Current in tkwant

Hi Rudolf, > The kwant documentation on kwant.solvers.common.GreensFunction() states > that calling this method will return the retarded Green's function. Does > this method evaluate the equilibrium or non-equilibrium retarded Green's > function? I am interested in the time-dependent non-equilibr

Re: [Kwant] Access to eigenvalue, eigenvector and number of points in each unit cell

Hi Sajad, > Dear all, > > I need to access to the number of atoms of my unit cell, > the eigenvalue and eigenvectors for each eigenvalue  of my Hamiltonian. > > Is there any one to help me and let me know if it is possible in kwan > to access them. > Could you post a short code example showing w

Re: [Kwant] Calculating the total energy in a superconducting lead

Hi Jannis, You mentioned that you system is infinite and has translational symmetry, yet you are using 'hamiltonian_submatrix'. 'hamiltonian_submatrix' probably does not return what you want; what should it return when the system is infinite, as it is in your case? Probably you want to construct

Re: [Kwant] Calculating the total energy in a superconducting lead

Hi again, I noticed my code example probably won't even run in the generic case; we need to do this wrangling with 'numpy.zeros_like' because 'inter_cell_hopping' returns a rectangular matrix in general (when only a subset of the sites in a unit cell connect via hoppings to the next unit cell). Pr

Re: [Kwant] Calculating the total energy in a superconducting lead

Hi Jannis, > > thank you for the fast response. You are probably right, that I need > to use the k-space Hamiltonian for the infinite case. Would my method > work for a finite system then? Potentially with periodic boundary > conditions? For a finite system (with or without PBC) you should dire

Re: [Kwant] matrix

Hi Nafise, > Dear all, > > Is there any one to know how we can use one element of matrix? For > example we have matrix A as follows: > > A=[2 4;6,0] > > We have A matrix with dimension 2*2. If  we want to use one element of > matrix such as A(2,1), (that is number 6 in the matrix), How we can > w

Re: [Kwant] Calculating the total energy in a superconducting lead

Hi Jannis, > It does make sense and helps a lot. > > Is there a way to calculate E_n(k) of a 2D infinite system in kwant? > 2D translational symmetric systems can't be finalized and > cell_hamiltionian and inter_cell_hopping don't work with wraparound > either. > This is something that we've wan

Re: [Kwant] What is the algorithm for calculating the mode decomposition

Hi Zhan, > > In the latest Kwant manual describing the details about > kwant.physics.modes, I find a sentence "This function uses the most > stable and efficient algorithm for calculating the mode decomposition > that the Kwant authors are aware about. Its details are to be > published." Do anyon

Re: [Kwant] What is the algorithm for calculating the mode decomposition

Me again, I just noticed that the notebook at http://tiny.cc/kwant-journal-club looks kind of wonky because nbviewer doesn't understand some of the markup I used. I've now made the notebook available on binder as well (even though there's no executable code really): http://tiny.cc/kwant-journal-

Re: [Kwant] What is the algorithm for calculating the mode decomposition

Hi Zhan, > > Thanks very much for your reply. Looking forward to the details in > your review article soon after. I wonder how kwant.physics.modes > obtain propagating modes, which can be used to calculate transport > observables.  > > As known, let \lambda=exp^{ik}, propagating modes have |\lamb

Re: [Kwant] Problems to add disorder to the Kitaev chain

Hi Luca, > syst[lat(0)] = -(1/2)*(mu + W*(2*onsite - 1))*pauli3 > > for i in range(1,L): > > syst[lat(i)] = -(1/2)*(mu + W*(2*onsite - 1))*pauli3 > > > syst[lat(i), lat(i - 1)] = -(t/2)*pauli3 + 1j*(Delta/2)*pauli2 > > -

Re: [Kwant] Problems to add disorder to the Kitaev chain

Hi Luca, > thanks again for your useful reply. > > If I understand correctly, then I am not sure > how to simulate the physics of disorder. > > Indeed, that task requires to create various > (in principle infinite in number) configurations, > measure some physical quantity on each of them, and th

[Kwant] How to obtain the retarded Green's function for a lead

Good day, I have a question about how best to obtain the retarded Green's function for a lead in Kwant. Kwant already has a way of calculating the retarded self-energy of a lead (the 'selfenergy' method of 'StabilizedModes' [1]), however there is no equivalent routine for the retarded Green's

[Kwant] Stability of the retarded Green's function calculation

Hello Kwantoptians, I have a question regarding the speed/stability of computing the retarded Green's function of a transport setup using Kwant. In the Kwant source-code [1] it is noted that using `kwant.greens_function` is "often slower and less stable than the scattering matrix calculation".

Re: [Kwant] Stability of the retarded Green's function calculation

or the scattering problem were "indicator vectors with 1s in [the] extended part". This is not true, however the interpretation of the RHS as a "single incoming mode" is correct AFAIK. Happy Kwanting, Joe From: Kwant-discuss On Behalf Of Joseph Weston (Aquent LLC - Canada)

Re: [Kwant] [EXTERNAL] Re: Stability of the retarded Green's function calculation

g what you said, but I would like a bit of clarity on this point. Thanks, Joe -Original Message- From: Anton Akhmerov Sent: Sunday, March 22, 2020 8:41 AM To: Joseph Weston (Aquent LLC - Canada) Cc: kwant-discuss@kwant-project.org Subject: [EXTERNAL] Re: [Kwant] Stability of the r

Re: [Kwant] [EXTERNAL] An issue with plotting two systems with different dimension in one system

Hi, The problem is that your ‘lat’ lattice exists in R^3, whereas your ‘honeycomb’ lattice exists in R^2. Kwant won’t try to guess what embedding you want to use for the ‘honeycomb’ lattice, so if you want to use both in the same system you will have to specify your honeycomb lattice using vect

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