Chern number calculation

[Dominik Gresch]

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.invariant.chern
<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 at iitgoa.ac.in
> <mailto:surasree183212004 at 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
>
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