Dear Rafael González,
When an integer is passed to the "bands" flag, it is interpreted as the /number/ of bands to take into account. In your example
* bands=0: is equivalent to bands=[] - there are no bands to compute the Chern number for, which is why it doesn't work * bands=1: is equivalent to bands=[0] - it computes the Chern number for the lower-energy bands * bands=[1] computes the Chern number for the higher-energy band (i.e., unoccupied) band - which has the opposite value * bands=[0,1] (equivalent to bands=2) - when the whole system (all bands) are included, it can be adiabatically connected to a trivial system
I hope this helps - let me know if things are still unclear.
Best regards,
Dominik
On 03.08.20 20:59, Rafael Gonzalez Hernandez wrote:
Dear z2pack, I used the code to understand the example of Haldane model. However, I changed the bands flag to test it and I found the Chern number for different values of:
band=0 chern= doesn't work band=1 chern=-1 band=[0] chern=-1 band=[1] chern=1 band=[0,1] chern=0
Why It is finding found a different between 1(both bands according to manual) and [0,1] bands? Thank you in advance for your help
Best regards,
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Rafael J. González Hernández
Profesor Asociado Departamento de Física. Of. 2-45. Bloque L-6. Tel. +57 5 3509509 Ext. 3425 E http://www.uninorte.edu.co/mail: rhernandezj@uninorte.edu.co mailto:rhernandezj@uninorte.edu.co
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