  FePS$_3$ is a prototype van der Waals layered antiferromagnet and a Mott
insulator under ambient conditions, which has been recently reported to go
through a pressure-induced dimensionality crossover and an insulator-to-metal
transition. These transitions also lead to the appearance of a novel magnetic
metallic state. To further understand these emergent structural and physical
properties, we have performed a first-principles study using van der Waals and
Hubbard $U$ corrected density functional theory including a random structure
search. Our computational study attempts to interpret the experimental
coexistence of the low- and intermediate-pressure phases and we predict a novel
high-pressure phase with distinctive dimensionality and different possible
origins of metallicity.
