Neutron generation via the mechanism adsorption of pressurized deuterium on an electron deficient titanium matrix. An MD–DFT combined analysis on the mechanism of the Ti–D bond formation

In the present paper the mechanism behind the neutron generation experiment in titanium lattice alloyed with deuterium atoms is investigated via both a static Density Functional Theory and a Molecular Dynamics approach. In particular, the hypothesized formation of a three-centre-two-electrons (3c-2e) bond, which is typical of electron-deficient species alloyed with H and its heavy isotopes (D, T), is investigated. In the context of the static analysis, a two-fold approach is taken into account, i.e., a cluster one to describe the bonding environment and the nature of the orbitals involved in such a bond, and a periodic one through which the occurrence of this peculiar feature is investigated as a function of deuterium atom concentrations in the Ti lattice. The octahedral subcell is found to be the most suitable site for the formation of this bond. A saturation value of two deuterium atoms for the 3c-2e bond per octahedral/tetrahedral subcell is also reported. Molecular Dynamics analysis performed at ordinary T by means of a Nose thermostat reveals the possibility for two deuterium atoms to occupy at the same time the Td and the Oh site of vicinal subcells.

► AIMD predicts the stable configuration for the 3c-2e Ti–D bond in Ti host. ► P & T impact in a different way on the collisional process. ► Different D concentrations favour different sites in the Ti host matrix. ► Compared to the elements of the Group 4 (Zr, Hf), Ti has the best affinity for D.