Dear Zhanzhi, I believe you missed the line "sys = sys.finalized()". Please use the Kwant tutorial to learn Kwant instead, it's a much more systematic source. Best, Anton On Tue, Jan 1, 2019 at 11:13 PM Zhanzhi Jiang <zhanzhi@utexas.edu> wrote:

Hi,

I am following the vedio tutorial provided by Christoph (https://kwant-project.org/doc/kwant-screencast-2014)

When I run

ldos = kwant.ldos(sys, 0.2)

There is an error "TypeError: Expecting an instance of System"

Then when I run

kwant.plotter.map(sys, ldos)

There is an error "NameError: name 'ldos' is not defined"

So I cannot get the map of the local DOS as shown in the vedio. It looks like the second error is a result of the first one. How could I solve this?

Best, Zhanzhi