Numerical modelling of hydrogen/deuterium absorption in transition- metal alloys

Multiple theories on hydrogen isotope fusion in Pd metal have been developed over the years. Among other important factors, the high concentration of H(D) atoms and their close proximity to each other within a host lattice are important. We use numerical modeling to investigate conditions favorable to lower H-H (D-D) separation. This separation depends on the background charge density within the lattice [1, 2]. Because of the high charge density in bulk Pd the internuclear distance between two hydrogen or deuterium atoms is larger than the value in vacuum [1]. However, the presence of lattice defects (vacancies [3], free-internal surfaces/cracks [4] and interstitials [5]) can lower the charge density down to the level which would promote the H2(D2) molecule formation at closer separation.