# Calculation of Flux Harmonics and Higher Eigenvalues

**URL:** <https://openmc.discourse.group/t/calculation-of-flux-harmonics-and-higher-eigenvalues/2066>\
**Category:** User Support\
**Created:** [May 23, 2022, 9:09pm UTC](https://openmc.discourse.group/t/calculation-of-flux-harmonics-and-higher-eigenvalues/2066 "2022-05-23T21:09:25Z")\
**Posts on this page:** 2\
**Page:** 1

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**Author:** ![RonaldGatchalian](https://avatars.discourse-cdn.com/v4/letter/r/db5fbb/32.png) [@RonaldGatchalian](https://openmc.discourse.group/u/RonaldGatchalian)\
**Post date:** [May 23, 2022, 9:09pm UTC](https://openmc.discourse.group/t/calculation-of-flux-harmonics-and-higher-eigenvalues/2066/1 "2022-05-23T21:09:25Z")

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Hi OpenMC community,

I am looking for methods to calculate higher eigenvalues and eigenmodes using OpenMC. I know Serpent has fission matrix capability, and MCNP seems to it have too in its R&D version. Any suggestions or useful reference on this subject matter?

Thank you very much.

Ronald

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**Author:** ![paulromano](https://yyz2.discourse-cdn.com/free1/user_avatar/openmc.discourse.group/paulromano/32/486_2.png) [@paulromano](https://openmc.discourse.group/u/paulromano)\
**Post date:** [August 16, 2022, 3:58am UTC](https://openmc.discourse.group/t/calculation-of-flux-harmonics-and-higher-eigenvalues/2066/2 "2022-08-16T03:58:08Z")

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Sorry this never got a response – the main version of OpenMC does not have a capability for computing the fission matrix at present. There have been a few research efforts / branches where such a capability was added, but it never made it back to the main branch of the code.