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Investigating hydrogen sorption in hydride-forming materials is essential for advancing a wide range of industrial technologies. Among such materials, LaNi$_5$ is a common candidate due to its ability to accommodate multiple hydride phases. Upon full hydrogenation, LaNi$_5$ forms the stable hydride phase LaNi$_5$H$_7$. Its properties such as lowering absorption and desorption pressures and enhancing resistance to repeated cycling can be improved through partial substitution.
In this work, we focused on LaNi$_{5-x}$Sn$_x$ compounds. Quantum-mechanical approaches play a crucial role in investigating hydride formation, particularly given the difficulty of experimentally resolving the precise crystal structures of these compounds, which further complicates subsequent thermodynamic analyses. Experiments-complementing Density Functional Theory (DFT) calculations provide key insights into ground-state properties, including equilibrium lattice parameters, formation energies, electronic density of states, and charge density distributions.
DFT calculations revealed that the compositions LaNi$_{4.88}$Sn$_{0.13}$ and LaNi$_{4.38}$Sn$_{0.63}$ exhibit the highest thermodynamic stability among the LaNi$_{5-x}$Sn$_x$ series. Increased Sn content in the investigated structures further influences the magnetic properties of the phases. The phase with a lower Sn concentration retains its magnetic character, whereas the phase with a higher Sn concentration becomes non-magnetic. These optimized structures subsequently serve as the basis for modeling the formation of the type H$_7$LaNi$_{5-x}$Sn$_x$ hydrides. This provides insight into how partial substitution of Ni by Sn affects hydrogen uptake and the stability of the resulting hydride phases.
Additionally, computational aspects of a technical character, such as the computational time requirements were analyzed with respect to the number of computational nodes and the internal parameters of the applied code, offering a practical perspective on the efficiency and scalability of such simulations at the IT4I supercomputing infrastructure.
Computational resources were provided by the e-INFRA CZ project (ID:90254), supported by the Ministry of Education, Youth and Sports of the Czech Republic. These resources were utilized through IT4Innovations National Supercomputing Center, MetaCentrum as well as CERIT Scientific Cloud. This work was created as part of the project No. CZ.02.01.01/00/22_008/0004631 Materials and technologies for sustainable development within the Jan Amos Komensky Operational Program financed by the European Union and from the state budget of the Czech Republic.
