Pressure-induced transitions in FePS$_3$: Structural, magnetic and electronic properties

I publish the authors' communication in this comment, so that the referees can read it and formulate a possible response.

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Dear Dr. Claudio Attaccalite,

Thank you for your insightful review of our manuscript and the opportunity to revise our paper. We appreciate the thorough assessment and constructive feedback provided by both referees. We have carefully considered their comments and suggestions and made necessary changes in the revised manuscript.

Regarding Referee 1's report, we have addressed the concerns raised, such as removing redundancy in the text and improving clarity. We appreciate the referee’s positive comments regarding the topic and results presented in our work, and we thank them for suggesting our work for publication.

In response to Referee 2's report,

1 ) We have expanded the introduction section to include recent papers on TMPX3 compounds and pressure-induced superconductors, as suggested by the second referee’s report: We have added [2D Mater. 10, 014008 (2023)] as an example of “clean energy generation related with photocatalytic water splitting applications”. We have added [J. Phys. Chem. C 126, 6791 (2022); Phys. Rev. B 106, 035137 (2022)] as monolayer manufacturing references. We have added [Nat. Commun. 5, 5508 (2014); Nat. Commun. 12, 5436 (2021); Proc. Natl. Acad. Sci.118, e2108938118 (2021); npj Quantum Mater. 7, 93 (2022)] to expand the pressure-induced superconductivity near antiferromagnetic order. We did not add [Nature 615, 244 (2023)] as the debate regarding this work is still underway. We have added [Phys. Rev. B 107, 075423 (2023)] to address the complexity of magnetic interactions in TMPX3.

2) In our paper, we have illustrated how the band gap shrinks with increasing pressure in LP and HP-I phases and the insulator-to-metal transition happens when HP-II-beta phase becomes the most energetically favourable phase. The dimensionality is explored as a function of the inter- and intralayer P-P distances. The HP-II-beta phase is 3D-connected by contrast to the HP-II phase, of which the interlayer distance gets suppressed but the van der Waals gap remains.

3) While we recognize the importance of establishing a theoretical model for FePS3, this is beyond the scope of the current study. We cannot delineate a simple model which addresses the insulator-to-metal transition, the magnetic ordering evolution and P-P interlayering bonding at the same time within the DFT+U framework. The models proposed by some of the previous studies are focusing on the magnetic interactions at ambient pressure. However, we will keep this suggestion in mind for the future studies.

Overall, we believe that these revisions have strengthened the manuscript and addressed the referees’ concerns. We hope that these revisions adequately address your concerns and that you find our manuscript suitable for publication in SciPost Physics.

Thank you again for considering our manuscript for publication. We look forward to hearing your decision.

Yours sincerely, Shiyu Deng, Siyu Chen, Bartomeu Monserrat, Emilio Artacho and Siddharth Saxena