Thermodynamic stability of N2 clathrate hydrates in the sI and sII structures is investigated using density functional theory with several exchange-correlation functionals, explicitly accounting for composition (cage occupancies) and pressure at T = 0 K. Among the tested functionals, revPBE-D3(0) best reproduces experimental lattice parameters and bulk moduli B0 . Energetic analyses confirm the strong impact of large cage double occupancy on sI, whereas the convex-hull results show that sI with single occupancy remains thermodynamically stable up to ∼ 0.8 GPa alongside sII with single occupancy. Increasing pressure then stabilizes sII with double occupancy, consistent with its larger large-cage volume and lower framework strain. These results provide a coherent, first-principles thermodynamic framework for N2 hydrate stability and a baseline for finite-temperature extension.
@article{arxiv.2512.16819,
title = {Thermodynamical study of N$_2$ clathrate hydrate from DFT calculations},
author = {L. Martin-Gondre and V. Meko Fotso and C. Métais and A. Patt and J. Ollivier and A. Desmedt},
journal= {arXiv preprint arXiv:2512.16819},
year = {2025}
}