Dear Joe, 

Thank you for your comments. You have greatly encouraged me to learn kwant more; I have never used spin before. 
And by training, I am a paleomagnetist not a  solid state physicist; so, multiplying the ldos just my wild idea.



> Date: Tue, 29 Sep 2015 13:57:18 +0200
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> CC:
> Subject: Re: [Kwant] ldos.cumsum or ldos.cumprod
> Hi again,
> > I am trying to investigate a graphene using kwant and I would like to see if any defect in the material (e.g. using del sys [a(0,0)] ) could make the material becomes magnetic. Can this transformation be indicated by some changes in DOS ? I enclose the python codes.
> I took a quick look at your notebook, but as far as I can tell you just
> put a spatially-varying potential on the sites of the ribbon. Given that
> you don't include spin anywhere in your model, I cannot see how you
> could ever have a magnetic effects which arise.
> Also I am not sure what you are trying to calculate. I do not know what
> multiplying the density of states on each site together corresponds to
> physically.
> I should probably say as well that we try to keep this mailing list
> specifically about Kwant, rather than about general physics questions.
> It seems that your question is more about general physics, than
> specifically how to do a particular (and well defined) thing in Kwant.
> I think that you may get more useful responses by posting on a specific
> physics forum, for example
> Hope that helps,
> Joe