# Creating non-local operators as sum of local operators

**URL:** <https://itensor.discourse.group/t/creating-non-local-operators-as-sum-of-local-operators/1011>\
**Category:** DMRG and Numerical Methods\
**Tags:** julia, dmrg, mpo\
**Created:** [July 10, 2023, 2:09pm UTC](https://itensor.discourse.group/t/creating-non-local-operators-as-sum-of-local-operators/1011 "2023-07-10T14:09:58Z")\
**Posts on this page:** 1\
**Page:** 1

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**Author:** ![Kaanonder](https://avatars.discourse-cdn.com/v4/letter/k/4af34b/32.png) [@Kaanonder](https://itensor.discourse.group/u/Kaanonder)\
**Post date:** [July 10, 2023, 2:09pm UTC](https://itensor.discourse.group/t/creating-non-local-operators-as-sum-of-local-operators/1011/1 "2023-07-10T14:09:59Z")

</div>

I’m trying to define a set of non-local operators such as

\tilde{c}\_{i}=\sum\_j f(i-j) c\_{ j}

with some function f and the sum over the full lattice. My goal is to first define such a \tilde{c}\_{i} which I can then use to construct interactions in a Hamiltonian.

I could try to do this in the Hamiltonian directly but it get’s very cumbersome so I’d like to first define \tilde{c}\_{i}, then plug it into my Hamiltonian. How should I go about this?

Thanks very much!