Oxidation States, Thouless’ Pumps, and Nontrivial Ionic Transport in Nonstoichiometric Electrolytes

Thouless’ quantization of adiabatic particle transport permits one 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 atom...

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Autores principales:	Paolo Pegolo, Federico Grasselli, Stefano Baroni
Formato:	article
Lenguaje:	EN
Publicado:	American Physical Society 2020
Materias:	Physics QC1-999
Acceso en línea:	https://doaj.org/article/533cbe27d79445eba8eef881f1ec5861
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spelling	oai:doaj.org-article:533cbe27d79445eba8eef881f1ec58612021-12-02T12:43:48ZOxidation States, Thouless’ Pumps, and Nontrivial Ionic Transport in Nonstoichiometric Electrolytes10.1103/PhysRevX.10.0410312160-3308https://doaj.org/article/533cbe27d79445eba8eef881f1ec58612020-11-01T00:00:00Zhttp://doi.org/10.1103/PhysRevX.10.041031http://doi.org/10.1103/PhysRevX.10.041031https://doaj.org/toc/2160-3308Thouless’ quantization of adiabatic particle transport permits one 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’ pump mechanism if the system were subject to a suitably defined time-periodic Hamiltonian. The occurrence of these requirements determines a nontrivial transport regime whereby charge can flow without any ionic convection, even in electronic insulators. These 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 nonstoichiometric 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 nontrivial transport regime such that most of the total charge current results to be uncorrelated from the ionic ones.Paolo PegoloFederico GrasselliStefano BaroniAmerican Physical SocietyarticlePhysicsQC1-999ENPhysical Review X, Vol 10, Iss 4, p 041031 (2020)
institution	DOAJ
collection	DOAJ
language	EN
topic	Physics QC1-999
spellingShingle	Physics QC1-999 Paolo Pegolo Federico Grasselli Stefano Baroni Oxidation States, Thouless’ Pumps, and Nontrivial Ionic Transport in Nonstoichiometric Electrolytes
description	Thouless’ quantization of adiabatic particle transport permits one 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’ pump mechanism if the system were subject to a suitably defined time-periodic Hamiltonian. The occurrence of these requirements determines a nontrivial transport regime whereby charge can flow without any ionic convection, even in electronic insulators. These 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 nonstoichiometric 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 nontrivial transport regime such that most of the total charge current results to be uncorrelated from the ionic ones.
format	article
author	Paolo Pegolo Federico Grasselli Stefano Baroni
author_facet	Paolo Pegolo Federico Grasselli Stefano Baroni
author_sort	Paolo Pegolo
title	Oxidation States, Thouless’ Pumps, and Nontrivial Ionic Transport in Nonstoichiometric Electrolytes
title_short	Oxidation States, Thouless’ Pumps, and Nontrivial Ionic Transport in Nonstoichiometric Electrolytes
title_full	Oxidation States, Thouless’ Pumps, and Nontrivial Ionic Transport in Nonstoichiometric Electrolytes
title_fullStr	Oxidation States, Thouless’ Pumps, and Nontrivial Ionic Transport in Nonstoichiometric Electrolytes
title_full_unstemmed	Oxidation States, Thouless’ Pumps, and Nontrivial Ionic Transport in Nonstoichiometric Electrolytes
title_sort	oxidation states, thouless’ pumps, and nontrivial ionic transport in nonstoichiometric electrolytes
publisher	American Physical Society
publishDate	2020
url	https://doaj.org/article/533cbe27d79445eba8eef881f1ec5861
work_keys_str_mv	AT paolopegolo oxidationstatesthoulesspumpsandnontrivialionictransportinnonstoichiometricelectrolytes AT federicograsselli oxidationstatesthoulesspumpsandnontrivialionictransportinnonstoichiometricelectrolytes AT stefanobaroni oxidationstatesthoulesspumpsandnontrivialionictransportinnonstoichiometricelectrolytes
_version_	1718393685779939328

Oxidation States, Thouless’ Pumps, and Nontrivial Ionic Transport in Nonstoichiometric Electrolytes

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