Evaluation of thermal neutron scattering law for light and heavy water based on molecular dynamics simulations

A molecular dynamics simulation based method has been implemented in nuclear data processing code NECP-Atlas to calculate the thermal scattering law (TSL) for liquid materials. In this method, the quantum self-scattering law is represented by Gaussian approximation, and the width function of quantum self-scattering law is obtained by applying a quantum correction on the classical width function, which is calculated based on molecular dynamics simulation. The Sköld approximation is applied to take account of the coherent effect of deuterium and oxygen in heavy water. The double differential scattering cross section, angular differential scattering cross section, average cosine of scattering angle, and integrated thermal scattering cross section of light and heavy water are calculated based on the TSL obtained in this work, and compared with experimental data, and those calculated based on ENDF/B-VIII.0 and JENDL-5. The results obtained in this work show good agreement with those based on ENDF/B-VIII.0 and JENDL-5.