Dear Surasree,

For computing the Chern number, you can use the "z2pack.invariant.chern" function (https://z2pack.greschd.ch/en/latest/reference/invariant.html#z2pack.invarian... https://z2pack.greschd.ch/en/latest/reference/invariant.html#z2pack.invariant.chern) instead of "z2pack.invariant.z2".

In terms of the surface used, you should use a surface that is completely closed, as opposed to the Z2 calculation where it only covers half the Brillouin zone.

So, for example: `lamba s, t: [0, s, t]`. The value of "X" in your example can be freely chosen for Chern number calculations. If the band structure has a direct gap everywhere the value should be the same for all X, if there are band gap closures it can change when crossing them.

Best regards,

Dominik

On 02.04.21 09:50, Surasree Sadhukhan wrote:

Is it like  [1, s / 2, t]  instead of  [0.5, s / 2, t] for chern number?? I want to say  [X, s / 2, t] X=0.5 for z2-number X=1.0 for Chern number. Please let me know

Thanks & Regards

Surasree Sadhukhan Research Scholar School Of Physical  Sciences IIT GOA

On Fri, Apr 2, 2021 at 1:15 PM Surasree Sadhukhan <surasree183212004@iitgoa.ac.in mailto:surasree183212004@iitgoa.ac.in> wrote:

Dear Sir,
Are there any extra tags to calculate the Chern number of a system
in Z2-pack software? I don't find any tags related to chern number
in run.py.

Thanks & Regards

Surasree Sadhukhan
Research Scholar
School Of Physical  Sciences
IIT GOA