{
  "annotation_id": "23ef6536-6fc0-484f-aec3-77043d761963",
  "date_created": "2026-03-02T18:01:00.067000Z",
  "date_modified": "2026-03-02T18:01:00.067000Z",
  "file_hash": "2b68d0ab3f695f5879a40539207d11978c54f7bb2c82beeae091e4805d636389",
  "private": false,
  "record": {
    "abstract": "We present an ab initio method of calculation of isotope shift and\nrelativistic shift in atoms with a few valence electrons. It is based on an\nenergy calculation involving combination of the configuration interaction\nmethod and many-body perturbation theory. This work is motivated by analyses of\nquasar absorption spectra that suggest that the fine structure constant, alpha,\nwas smaller at an early epoch. Relativistic shifts are needed to measure this\nvariation of alpha, while isotope shifts are needed to resolve systematic\neffects in this study. The isotope shifts can also be used to measure isotopic\nabundances in gas clouds in the early universe, which are needed to study\nnuclear reactions in stars and supernovae and test models of chemical\nevolution. This paper shows that isotope shift in magnesium can be calculated\nto very high precision using our new method.",
    "arxiv_id": "physics/0507062",
    "authors": [
      "J. C. Berengut",
      "V. V. Flambaum",
      "M. G. Kozlov"
    ],
    "categories": [
      "physics.atom-ph",
      "astro-ph"
    ],
    "doi": "10.1103/PhysRevA.72.044501",
    "journal_ref": "Phys.Rev.A72:044501,2005",
    "title": "Improved calculation of relativistic shift and isotope shift in Mg I",
    "url": "https://arxiv.org/abs/physics/0507062"
  },
  "schema_id": "dorsal/arxiv",
  "source": {
    "execution_id": "bb0cb1a0-d40c-410f-8528-9752f140d85d",
    "id": "arXiv Dataset IDs",
    "type": "Model",
    "variant": "snapshot-2026-03-01",
    "version": "0.1.0"
  },
  "user_id": 1000002
}