{"content-origin" "https://www.ctcms.nist.gov/potentials/entry/2022--Sun-Y-Zhang-F-Mendelev-M-I-et-al--Fe/" "contributor-id" "4ad03136-ed7f-4316-b586-1e94ccceb311" "description" "This is an EAM potential developed to simulate the solidification of Fe under the Earth's inner core conditions." "developer" ["2f1a5a31-41fe-4067-9fff-0c2a77531659" "cacf07e3-17ff-4374-9109-4340ba3d9d07" "f3251c9e-5721-45a2-a0fc-1e48977d95e2" "03954da3-1541-46e3-8e88-f3e564ba5840" "18284431-0bd8-477f-b391-eadc15ec7053"] "doi" "10.25950/cfa6938b" "domain" "openkim.org" "executables" [] "extended-id" "EAM_Dynamo_SunZhangMendelev_2022_Fe__MO_044341472608_000" "funding" [{"award-number" "EAR-1918134, EAR-1918126, ACI-1548562" "funder-identifier" "https://doi.org/10.13039/100000001" "funder-identifier-type" "Crossref Funder ID" "funder-name" "National Science Foundation" "scheme-uri" "http://doi.org/"} {"award-number" "DE-SC0019759" "funder-identifier" "https://doi.org/10.13039/100000015" "funder-identifier-type" "Crossref Funder ID" "funder-name" "U.S. Department of Energy" "scheme-uri" "http://doi.org/"}] "kim-api-version" "2.2" "maintainer-id" "4ad03136-ed7f-4316-b586-1e94ccceb311" "model-driver" "EAM_Dynamo__MD_120291908751_005" "potential-type" "eam" "publication-year" "2022" "source-citations" [{"abstract" "Understanding the formation of the Earth’s inner core is essential to understanding the geodynamo and Earth's history. However, recent attempts to explain the initial solidification of the inner core have been unsuccessful. The supercooling necessary to form hcp iron is unrealistically large and creates the “inner core nucleation paradox.” Our work demonstrates that molten iron can crystallize via a two-step nucleation process involving the intermediate bcc phase under core conditions. This mechanism significantly reduces the required undercooling necessary to nucleate solid iron. This work also suggests that bcc and hcp iron have similar free energies at pressures near the inner core center. The Earth's inner core started forming when molten iron cooled below the melting point. However, the nucleation mechanism, which is a necessary step of crystallization, has not been well understood. Recent studies have found that it requires an unrealistic degree of undercooling to nucleate the stable, hexagonal, close-packed (hcp) phase of iron that is unlikely to be reached under core conditions and age. This contradiction is referred to as the inner core nucleation paradox. Using a persistent embryo method and molecular dynamics simulations, we demonstrate that the metastable, body-centered, cubic (bcc) phase of iron has a much higher nucleation rate than does the hcp phase under inner core conditions. Thus, the bcc nucleation is likely to be the first step of inner core formation, instead of direct nucleation of the hcp phase. This mechanism reduces the required undercooling of iron nucleation, which provides a key factor in solving the inner core nucleation paradox. The two-step nucleation scenario of the inner core also opens an avenue for understanding the structure and anisotropy of the present inner core." "author" "Sun, Yang and Zhang, Feng and Mendelev, Mikhail I. and Wentzcovitch, Renata M. and Ho, Kai-Ming" "doi" "10.1073/pnas.2113059119" "eprint" "https://www.pnas.org/doi/pdf/10.1073/pnas.2113059119" "journal" "Proceedings of the National Academy of Sciences" "number" "2" "pages" "e2113059119" "recordkey" "MO_044341472608_000a" "recordprimary" "recordprimary" "recordtype" "article" "title" "Two-step nucleation of the {E}arth's inner core" "url" "https://www.pnas.org/doi/abs/10.1073/pnas.2113059119" "volume" "119" "year" "2022"}] "species" ["Fe"] "title" "EAM potential (LAMMPS cubic hermite tabulation) for Fe developed by Sun et al. (2022) v000"}