Exploring negative linear compressibility in the orthorhombic polymorph of ScF₃ space group C222 under high pressure

This study investigates the orthorhombic polymorph of ScF₃ (C222) under hydrostatic pressure, revealing negative linear compressibility (NLC) along the b-axis. First-principles calculations show anisotropic expansion (b-axis) and contraction (a-, c-axes), with compressibility coefficients quantified up to 40 GPa. The findings advance the understanding of pressure-induced behaviors in ScF₃ and its potential for functional materials design.

First-principles calculations were performed using density functional theory (DFT) within the generalized gradient approximation (GGA) framework as implemented in CASTEP. Lattice parameters and elastic properties were computed under varying pressure conditions. The Pascal program was used to determine compressibility coefficients and analyze NLC behavior. Computational settings, including energy cutoffs, k-point sampling, and convergence criteria, were optimized for accuracy and stability.