Hi, Hanlin Liu wrote:

When I use the KPM method in KWANT, the longitudinal conductivity at zero point of graphite is around 1.03, but according to the literature it should be (4/ π).，The difference between the two is large, so I would like to ask what the specific reason is.

Without a clean minimal example that demonstrates your problem it is unlikely that anyone will be able to help you. But even if you can provide a useful example, the inability to reproduce a particular literature result goes beyond the scope of this list. It’s a different story if you believe that a bug or problem in Kwant might be the culprit, but then please try to provide some evidence. Christoph