Specify sites in npdm

[cfengno1]

Dear Huanchen,

I am trying to calculate correlation functions for a specific range of sites, e.g. in a cylinder geometry by fixing site i and change site j along the same leg. I see that get_npdm() function does not have parameters that specify the range of sites, but instead it calculate all sites.

Is there an easy way to specify the range of sites?

Best,
Feng

[hczhai]

With block2==0.5.4rc2, you can now use the index_masks argument in DMRGDriver.get_npdm to set the desired range of sites for each operator in the correlation function. Detailed example can be found in the updated documentation: https://block2.readthedocs.io/en/latest/tutorial/custom-hamiltonians.html#Correlation-Functions.

[cfengno1]

Thank you Huanchen. This is awesome!