Title

Symmetry-dictated first-principles theory of purely ionic thermoelectricity

Alternative Title

순수 이온 열전의 대칭성 기반 제일원리 이론

DGIST Authors

Byeoksong Lee ; Joongoo Kang ; Byungki Ryu

Advisor

강준구

Co-Advisor(s)

Byungki Ryu

Issued Date

2026

Awarded Date

2026-02-01

Type

Thesis

Description

Thermoelectricity, Linear response, Atomic energy, Gauge invariance, Renormalization, Ionic transverse thermoelectricity

Table Of Contents

Ⅰ. Introduction 1
1.1 Outline of the thesis 3
ⅠI. Non-equilibrium thermodynamics 5
2.1 Entropy production 6
2.2 The kinetic coefficients 7
2.3 Onsager’s reciprocal relations 9
2.4 Green-Kubo theory of linear response 11
ⅠII. Gauge invariant theory of ionic thermoelectricity 14
3.1 Notations 14
3.2 Arbitrariness of atomic energy 15
3.2.1 Gauge freedom in atomic energy decomposition 15
3.2.2 Invariance of particle number flux 18
3.2.3 Energy flux vs. heat flux 19
3.3 Global gauge invariance 19
3.4 Local gauge invariance 22
3.5 Thermoelectricity and geometrical interpretation 24
3.5.1 Definition of ionic charge flux and ionic thermoelectricity 24
3.5.2 Geometrical interpretation of transport coefficient 25
3.5.3 Ionic vs. electronic Seebeck effects 27
3.6 Numerical experiments 27
3.6.1 Cu2S: a solid-liquid hybrid ionic conductor 28
3.6.2 Li3N: a layered ionic conductor with ambipolar Seebeck effect 29
3.6.3 Ionic transverse thermoelectricity 31
ⅠV. Related work 35
4.1 Gauge invariance in heat transport 34
4.2 Topological invariance of charge transport 34
4.3 Statistical refinement of the ionic Seebeck coefficient 36
4.4 Mechanistic interpretation of giant ionic thermoelectricity 37
V. Summary 38
VI. Appendices 40
6.1 MLP ensemble generation 40
6.2 Renormalization of partial enthalpies 41
6.3 Local gauge invariance and single-particle energies 42
6.4 Ab initio-quality MD simulations 43
6.5 Training and accuracy of ML potentials 44
6.5.1 GAP training for -Cu2S 45
6.5.2 On-the-fly MLP training 45
6.6 Numerical calculations of renormalized partial enthalpies 49
6.6.1 NPT vs. NVT ensembles 51
6.6.2 Error estimation with block averages 52
6.7 Topological quantization of ionic transport 55
6.8 Transport coefficients of -Cu2S and -Li3N 56
References 58
Korean summary 62

URI

https://scholar.dgist.ac.kr/handle/20.500.11750/59640
http://dgist.dcollection.net/common/orgView/200000942227

DOI

10.22677/THESIS.200000942227

Degree

Doctor

Department

Department of Physics and Chemistry

Publisher

DGIST

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