Recombination of Autodissociated Water Ions in a Nanoscale Pure Water Droplet

Acknowledgement

We thank Karnamohit Ranka (Lawrence Berkeley National Laboratory), Sirui Li (Los Alamos National Laboratory), and Tod Pascal (University of California, San Diego) for helpful discussions and KR for a critical reading of the manuscript. This work was supported by the Liquid Sunlight Alliance, which is supported by the US Department of Energy, Office of Science, Office of Basic Energy Sciences, Fuels from Sunlight Hub under award no. DE-SC0021266 and by an individual fellowship from the Resnick Sustainability Institute at Caltech (S.K.). This work used Stampede3 at Texas Advanced Computing Center through allocation DMR160114 from the Advanced Cyberinfrastructure Coordination Ecosystem: Services & Support (ACCESS) program, which is supported by National Science Foundation grants #2138259, #2138286, #2138307, #2137603, and #2138296. This research also used resources of the National Energy Research Scientific Computing Center; a DOE Office of Science User Facility supported by the Office of Science of the U.S. Department of Energy under Contract No. DE-AC02-05CH11231 using NERSC award BES-ERCAP0024109 for some calculations. Some computations were conducted on the Resnick High Performance Computing Center, a facility supported by Resnick Sustainability Institute at the California Institute of Technology.

Copyright and License

Copyright © 2025 American Chemical Society

Data Availability

The data underlying this study are available in the published article and its online Supporting Information.

Supplemental Material

The Supporting Information is available free of charge at https://pubs.acs.org/doi/10.1021/jacs.4c15103.

• HOMO–LUMO energy gap in ionic system with different functionals, equilibration temperature and energy trajectories, O–O radial distribution functions for H₃O⁺ and OH^–, schematics of hydrogen bond (HB) network and its direction for Dijkstra’s algorithm, detailed trajectory of the recombination process, normalized power spectra of H₃O⁺, OH^–, and H₂O and the time-dependent ion trajectories from the RexPoN simulation, the time evolution of the minimum internal angle along the water wire, and details of 2PT analysis (PDF)

• ReQM dynamics: ion diffusion in the inner region of 18 000 H₂O’s, Supporting Movie S1 (MOV)

• ReQM dynamics: ion diffusion on the surface of 18 000 H₂O’s, Supporting Movie S2 (MOV)

• ReQM dynamics: ion recombination in the inner region of 18 000 H₂O’s, Supporting Movie S3 (MOV)

• ReQM dynamics: ion recombinationon the surface of 18 000 H₂O’s, Supporting Movie S4 (MOV)

• ReQM dynamics: ion recombination in the inner region of 300 H2O’s, Supporting Movie S5 (MOV)

• ReQM dynamics: ion recombination on the surface of 300 H2O’s, Supporting Movie S6 (MOV)

• Time-dependent ion distance for H₃O⁺ and OH^–, wire length for H₃O⁺ and OH^–, number of hydrogen bonds along the wire for H₃O⁺ and OH^–, atom ID for H₃O⁺ and OH^– during ReQM recombination simulations in the inner region and at the surface of 18 000 H2O’s and 300 H2O’s (TXT, TXT, TXT, TXT)

• ASE python interface for Jaguar (TXT)

• Python library for QM region sampling of adaptive QM/MM scheme (TXT)

Contributions

S.K. and P.P. contributed equally to this work.

Conflict of Interest

The authors declare no competing financial interest.