{
  "annotation_id": "d3b2455d-f5e4-4f64-9167-ee33c0c1915e",
  "date_created": "2026-02-17T05:53:24.340000Z",
  "date_modified": "2026-02-17T05:53:24.340000Z",
  "file_hash": "01a87948b9e7c9a7ba5418efb78989787a1513c142270a677b12ae3b504bce97",
  "private": false,
  "record": {
    "abstract": "The hydration of magnesium oxide (MgO) to magnesium hydroxide (Mg(OH)$_2$) is a fundamental solid-surface chemical reaction with significant implications for materials science. Yet its molecular-level mechanism from water adsorption to Mg(OH)$_2$ nucleation and growth remains elusive due to its complex and multi-step nature. Here, we elucidate the molecular process of MgO hydration based on structures of the MgO/water interface obtained by a combined computational chemistry approach of potential-scaling molecular dynamics simulations and first-principles calculations without any a priori assumptions about reaction pathways. The result shows that the Mg$^{2+}$ dissolution follows the dissociative water adsorption. We find that this initial dissolution can proceed exothermically even from the defect-free surface with an average activation barrier of $\\sim$12 kcal/mol. This exothermicity depends crucially on the stabilization of the resulting surface vacancy, achieved by proton adsorption onto neighboring surface oxygen atoms. Further Mg$^{2+}$ dissolution then occurs in correlation with proton penetration into the solid. Moreover, we find that the Mg(OH)$_2$ nucleation and growth proceeds according to the dissolution-precipitation mechanism, rather than a solid-state reaction mechanism involving a direct topotactic transformation. In this process, Mg$^{2+}$ ions migrate away from the surface and form amorphous Mg-OH chains as precursors for Mg(OH)$_2$ nucleation. We also demonstrate that sufficient water facilitates the formation of more ordered crystalline nuclei. This computational study provides a comprehensive molecular-level understanding of MgO hydration, representing a foundational step toward elucidating the mechanisms of this class of complex and multi-step solid-surface chemical reactions.",
    "arxiv_id": "2601.10186",
    "authors": [
      "Taichi Inagaki",
      "Miho Hatanaka"
    ],
    "categories": [
      "cond-mat.mtrl-sci"
    ],
    "doi": "10.1021/acs.jpcc.5c06767",
    "license": "http://arxiv.org/licenses/nonexclusive-distrib/1.0/",
    "title": "Comprehensive Molecular-level Understanding of MgO Hydration through Computational Chemistry",
    "url": "https://arxiv.org/abs/2601.10186",
    "version": "v1"
  },
  "schema_id": "dorsal/arxiv",
  "source": {
    "execution_id": "7a008f72-c2d7-4127-8513-27636a96bc03",
    "id": "arXiv Dataset",
    "type": "Model",
    "variant": "snapshot-2026-01-17",
    "version": "0.1.0"
  },
  "user_id": 1000002
}