yunhuangzhang

Thank you @jlconlin for your quick response. Besides the M&C paper, you can find the [article preprint](https://www.researchgate.net/publication/338410350_Analytic_Evaluation_of_Hydrogen_Neutron_Elastic_Scattering_Moments_with_Free-Gas_Thermal_Treatment_Compared_to_NJOY) on my RG homepage, where we used analytic model to justify the need...

I totally agree with @jchsublet and @marquezj. Current the two-body model presented in our paper is only based on free-gas hydrogen. Therefore one should be very cautious when applying it...

> @yunhuangzhang did you test this with materials with a coherent-elastic component (graphite, beryllium)? GROUPR has a hard coded limit of 10 eV for Bragg-edge treatment and might complicate things....

FYI, the paper was accepted and now available online. [Analytic evaluation of hydrogen neutron elastic scattering moments with free-gas thermal treatment compared to NJOY .pdf](https://github.com/njoy/NJOY2016/files/4654578/Analytic.evaluation.of.hydrogen.neutron.elastic.scattering.moments.with.free-gas.thermal.treatment.compared.to.NJOY.pdf)