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Basic introduction to NCrystal

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Included references to the main papers and documentation
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Jose Ignacio Marquez Damian 2022-11-17 13:47:03 +01:00 • committed by GitHub
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docs/source/methods/cross_sections.rst
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@ -178,6 +178,24 @@ been selected. There are three methods available:
section data is loaded for a single temperature and is used in the
unresolved resonance and fast energy ranges.
------------------
NCrystal materials
------------------
As an alternative of the standard thermal scattering treatment using :math:`S(\alpha,\beta)`
tables, OpenMC allows to create materials using NCrystal_. In addition to the regular thermal elastic,
and thermal inelastic processes, NCrystal allows the generation of models for materials that
cannot currently included in ACE files such as oriented single crystals (see the `NCrystal paper`_),
and further extend the physics `using plugins`_. Thermal scattering kernels are generated on
the fly from dynamic and structural data, or loaded from :math:`S(\alpha,\beta)` tables converted
from ENDF6 evaluations. These kernels are sampled in a direct way using a fast `rejection algorithm`_
that does not require previous processing. A `large library` of materials is already included in
the NCrystal distribution, and new materials can be easily defined from scratch in the `NCMAT format`
or `combining existing files`.
The compositions of the materials defined in NCrystal are passed on to OpenMC all other reactions
except for thermal neutron scattering are handled by continuous energy ACE libraries.
----------------
Multi-Group Data
----------------
@ -279,3 +297,10 @@ or even isotropic scattering.
.. _ENDF/B data: https://www.nndc.bnl.gov/endf-b8.0/
.. _Leppanen: https://doi.org/10.1016/j.anucene.2009.03.019
.. _algorithms: http://ab-initio.mit.edu/wiki/index.php/Faddeeva_Package
.. _NCrystal: https://github.com/mctools/ncrystal
.. _NCrystal paper: https://doi.org/10.1016/j.cpc.2019.07.015
.. _using plugins: https://doi.org/10.1016/j.cpc.2021.108082
.. _rejection algorithm: https://doi.org/10.1016/j.jcp.2018.11.043
.. _large library: https://github.com/mctools/ncrystal/wiki/Data-library
.. _NCMAT format: https://github.com/mctools/ncrystal/wiki/NCMAT-format
.. _combining existing files: https://github.com/mctools/ncrystal/wiki/Announcement-Release3.0.0#2-multiphase-materials