We request beamtime on D19 to continue the crystallographic de novo phasing methodological proof-of-principle using enriched 113-Cd substituted perdeuterated Pyrococcus furiosus rubredoxin. Perdeuterated rubredoxin crystals are particularly suitable for this neutron anomalous study because of their stability and by the quality of the diffraction data usually obtained. The previous ILL Proposal 1-20-32 allowed us to successfully collect neutron anomalous differences on a 113Cd enriched crystal at 295K. The tests performed yielded high quality but incomplete data to 1.59 Å resolution. The practical demonstration of a protein structure being phased using anomalous neutron diffraction data using anomalous neutron dispersion requires complete neutron anomalous data, which was never performed before. This proposal aims to finish the evaluation and development of neutron de novo phasing of macromolecular protein structures and to further add anomalous neutron dispersion phasing methodology to the list of techniques available for D19's biological user base.