{
  "abstract": "Molecular-scale occupancy distributions in water and hard-sphere fluids can appear remarkably Gaussian. Using classical density functional theory with an external field conjugate to the occupancy, we calculate occupancy cumulants for spherical volumes in a hard-sphere fluid and reproduce the variance and small, oscillatory third moment reported previously in Monte Carlo simulations. This agreement shows that the density functional captures the correlations responsible for the phenomenon and allows the role of excluded-volume packing to be isolated. By comparison with the Poisson limit and by varying both observation-volume size and bulk density, we show that excluded-volume correlations strongly suppress the higher cumulants. The resulting skewness and excess kurtosis remain nonzero and oscillatory, but they become small as the observation volume increases. However, over the same molecular-scale range, the finite-volume variance remains strongly scale-dependent and does not attain the extensive scaling set by the bulk compressibility. The early onset of near-Gaussianity is therefore governed primarily by molecular packing: it does not demonstrate that the fluctuations have reached the thermodynamic Gaussian limit, nor does it support a distinct small-cavity regime governed by bulk-like Gaussian fluctuations.",
  "abstract_shown": true,
  "affiliations": [
    "H. H. Wills Physics Laboratory",
    "University of Bristol"
  ],
  "article_type": null,
  "arxiv": null,
  "author_total": 1,
  "authors": [
    {
      "affs": [
        0,
        1
      ],
      "name": "Nigel B. Wilding",
      "orcid": "0000-0003-1385-8674"
    }
  ],
  "bibtex": "https://research.draconitic.com/paper/dhrrc92ttdj21.bib",
  "cited_by": 0,
  "doi": "10.26434/chemrxiv.15009134/v1",
  "fulltext_url": null,
  "id": "dhrrc92ttdj21",
  "issns": [],
  "landing_url": "https://chemrxiv.org/doi/full/10.26434/chemrxiv.15009134/v1",
  "language": null,
  "licence": "CC-BY-NC-ND",
  "licence_label": "CC BY-NC-ND",
  "licence_source": "journal",
  "licence_url": "https://creativecommons.org/licenses/by-nc-nd/4.0/",
  "metadata_licence": null,
  "native_subjects": [
    [
      "openalex",
      "1606|Advanced Physical and Chemical Molecular Interactions"
    ]
  ],
  "openalex": "W7213922904",
  "pdf_url": "https://chemrxiv.org/doi/pdf/10.26434/chemrxiv.15009134/v1",
  "pmcid": null,
  "pmid": null,
  "published": "2026-09-21",
  "publisher": "American Chemical Society (ACS)",
  "ris": "https://research.draconitic.com/paper/dhrrc92ttdj21.ris",
  "sources": [
    {
      "first_seen": "2026-10-30T12:17:19Z",
      "native_id": "10.26434/chemrxiv.15009134",
      "source": "chemrxiv",
      "url": "https://chemrxiv.org/doi/full/10.26434/chemrxiv.15009134/v1"
    }
  ],
  "subjects": [
    {
      "field": "chemistry",
      "origin": "openalex:1606|Advanced Physical and Chemical Molecular Interactions",
      "subfield": "physical"
    }
  ],
  "title": "Why Molecular-Scale Occupancy Fluctuations Appear Gaussian without Being Bulk-Like",
  "title_text": "Why Molecular-Scale Occupancy Fluctuations Appear Gaussian without Being Bulk-Like",
  "type": "preprint",
  "updated_at": "2026-10-30T12:17:19Z",
  "url": "https://research.draconitic.com/paper/dhrrc92ttdj21",
  "venue": "ChemRxiv",
  "versions": []
}