Dear Camilla, It seems that you are trying to install Kwant on windows. This is a very hard task, and I fear none of the Kwant developers has enough knowledge of it right now (our Windows packages are built by Christoph Gohlke, see [1] for the build environment description). However if you are using windows 10, I suggest to try to install Kwant using the windows subsystem for linux. That way the standard Ubuntu build procedure should work for you.
Best, Anton [1]: http://www.lfd.uci.edu/~gohlke/pythonlibs/ On Mon, Jan 16, 2017 at 9:45 AM, Camilla Espedal <camilla.espe...@ntnu.no> wrote: > Thanks a lot. I tried to install the cons_laws_combined, but I get the > following error message: > > "LINK: fatal error LNK1181: cannot open input file 'lapack.lib'" > > Is there some package or installation I am missing? > > Best regards, > Camilla > > -----Original Message----- > From: anton.akhme...@gmail.com [mailto:anton.akhme...@gmail.com] On Behalf Of > Anton Akhmerov > Sent: 8. januar 2017 16:35 > To: Tómas Örn Rosdahl <torosd...@gmail.com> > Cc: Camilla Espedal <camilla.espe...@ntnu.no>; kwant-discuss@kwant-project.org > Subject: Re: [Kwant] Regarding smatrix and spin > > Hi Camilla, everyone, > > I've slightly modified Tómas's example to a case where the spins do get > coupled, check it out: > http://nbviewer.jupyter.org/url/antonakhmerov.org/misc/spin_conductance.ipynb > > I've also provided more detailed installation instructions in the notebook. > > Cheers, > Anton > > On Sun, Jan 8, 2017 at 2:45 PM, Tómas Örn Rosdahl <torosd...@gmail.com> wrote: >> Dear Camilla, >> >> For a Hamiltonian with degeneracies due to a conservation law, the >> scattering states will in general not have a definite value of the >> conservation law. In your case, Kwant returns scattering states that >> are arbitrary linear combinations of spin up and down, so it is not >> possible to label the amplitudes in the scattering matrix by spin. >> >> However, in Kwant 1.3 a feature will be added that allows for the >> construction of scattering states with definite values of a >> conservation law. See here for an explanation of the basic idea behind the >> algorithm. >> >> We're currently working on implementing this feature in Kwant itself. >> The good news is that we're practically done - here is a link to a git >> repo with a functioning implementation. After you clone the repo, >> check out the branch cons_laws_combined, which contains a version of >> Kwant with conservation laws implemented. This notebook contains a >> simple example to illustrate how to work with conservation laws and the >> scattering matrix. >> >> I invite you and anyone else who is interested to give it a try. We'd >> appreciate any feedback! >> >> In your case specifically, there would be two projectors in the new >> implementation - P0 which projects out the spin up block, and P1 that >> projects out the spin down block. If they are specified in this order, >> then the spin up and down blocks in the Hamiltonian have block indices >> 0 and 1, respectively. In the new implementation, it is possible to >> ask for subblocks of the scattering matrix relating not only any two >> leads, but also any two conservation law blocks in any leads. To get >> the reflection amplitude of an incident spin up electron from lead 0 >> into an outgoing spin down electron in lead 0, you could simply do >> smat.submatrix((0, 1), (0, 0)). Here, the arguments are tuples of indices >> (lead index, block index). >> >> Best regards, >> Tómas >> >> On Fri, Jan 6, 2017 at 3:46 PM, Camilla Espedal >> <camilla.espe...@ntnu.no> >> wrote: >>> >>> Hi again, >>> >>> >>> >>> This question is basically the same as this: >>> https://www.mail-archive.com/kwant-discuss@kwant-project.org/msg00076 >>> .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 >> >>
