Oxidation states, Thouless' pumps, and nontrivial ionic transport in nonstoichiometric electrolytes

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{
  "metadata": {
    "is_last": false, 
    "version": 1, 
    "title": "Oxidation states, Thouless' pumps, and nontrivial ionic transport in nonstoichiometric electrolytes", 
    "keywords": [
      "Transport properties", 
      "Thouless' pump", 
      "Solvation", 
      "Charge transport", 
      "MaX"
    ], 
    "description": "Thouless\u2019 quantization of adiabatic particle transport permits to associate an integer topological charge with each atom of an electronically gapped material. If these charges are additive and independent of atomic positions, they provide a rigorous definition of atomic oxidation states and atoms can be identified as integer-charge carriers in ionic conductors. Whenever these conditions are met, charge transport is necessarily convective, i.e. it cannot occur without substantial ionic flow, a transport regime that we dub trivial. We show that the topological requirements that allow these conditions to be broken are the same that would determine a Thouless\u2019 pump mechanism if the system were subject to a suitably defined time-periodic Hamiltonian. The occurrence of these requirements determines a non-trivial transport regime whereby charge can flow without any ionic convection, even in electronic insulators.\nThese results are first demonstrated with a couple of simple molecular models that display a quantum pump mechanism upon introduction of a fictitious time dependence of the atomic positions along a closed loop in configuration space. We finally examine the impact of our findings on the transport properties of non-stoichiometric alkali-halide melts, where the same topological conditions that would induce a quantum pump mechanism along certain closed loops in configuration space also determine a non-trivial transport regime such that most of the total charge current results to be uncorrelated from the ionic ones.\nIn this record we collect the time series of the electric currents, displaced dipoles, and energy band gaps supporting the plots and relevant results supporting our findings.", 
    "license": "Creative Commons Attribution 4.0 International", 
    "references": [
      {
        "url": "https://arxiv.org/abs/2006.16749", 
        "citation": "P. Pegolo, F. Grasselli, S. Baroni, arXiv:2006.16749 (2020)", 
        "type": "Preprint"
      }
    ], 
    "doi": "10.24435/materialscloud:jg-km", 
    "conceptrecid": "575", 
    "publication_date": "Oct 13, 2020, 00:04:19", 
    "edited_by": 100, 
    "_oai": {
      "id": "oai:materialscloud.org:576"
    }, 
    "contributors": [
      {
        "affiliations": [
          "SISSA\u2014Scuola Internazionale Superiore di Studi Avanzati, 34136 Trieste, Italy"
        ], 
        "email": "ppegolo@sissa.it", 
        "familyname": "Pegolo", 
        "givennames": "Paolo"
      }, 
      {
        "affiliations": [
          "SISSA\u2014Scuola Internazionale Superiore di Studi Avanzati, 34136 Trieste, Italy", 
          "COSMO\u2014Laboratory of Computational Science and Modelling, IMX, \u00c9cole Polytechnique F\u00e9d\u00e9rale de Lausanne, 1015 Lausanne, Switzerland"
        ], 
        "email": "fgrassel@sissa.it", 
        "familyname": "Grasselli", 
        "givennames": "Federico"
      }, 
      {
        "affiliations": [
          "SISSA\u2014Scuola Internazionale Superiore di Studi Avanzati, 34136 Trieste, Italy", 
          "CNR\u2014Istituto Officina dei Materiali, SISSA, 34136 Trieste, Italy"
        ], 
        "email": "baroni@sissa.it", 
        "familyname": "Baroni", 
        "givennames": "Stefano"
      }
    ], 
    "owner": 225, 
    "license_addendum": null, 
    "mcid": "2020.118", 
    "_files": [
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        "size": 649335, 
        "checksum": "md5:95b331dc15bc65115a95b0925e348fc7", 
        "description": "Data to be analyzed to reproduce the relevant results of the paper.", 
        "key": "Data.zip"
      }, 
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        "checksum": "md5:1e0df5fd19b00984f953bf877c60e3d5", 
        "description": "Jupyter notebook with the code to analyze the data.", 
        "key": "data_analysis.ipynb"
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        "description": "Readme file.", 
        "key": "README.md"
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    ], 
    "id": "576", 
    "status": "published"
  }, 
  "revision": 5, 
  "updated": "2020-10-21T10:40:15.893756+00:00", 
  "created": "2020-10-08T18:24:41.325267+00:00", 
  "id": "576"
}