Development of time-dependent second-principles simulations to study the transport and optical properties of materials
ABSTRACT: One of the most important properties of matter is its response to the application of external electric fields. The control of this phenomenon is is behind much of the current technology. A microscopic understanding of the mechanisms behind charge transport started with Drude at the beginni...
| Autor: | |
|---|---|
| Tipo de recurso: | tesis de maestría |
| Fecha de publicación: | 2021 |
| País: | España |
| Institución: | Universidad de Cantabria (UC) |
| Repositorio: | UCrea Repositorio Abierto de la Universidad de Cantabria |
| Idioma: | inglés |
| OAI Identifier: | oai:repositorio.unican.es:10902/25154 |
| Acceso en línea: | http://hdl.handle.net/10902/25154 |
| Access Level: | acceso abierto |
| Palabra clave: | Charge transport Second principles model Localization Wannier functions Band disentanglement Fatbands Orbital character Transporte de carga Modelo de segundos principios Localización Funciones de Wannier Desentrelazamiento de bandas Carácter orbital |
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| dc.title.none.fl_str_mv |
Development of time-dependent second-principles simulations to study the transport and optical properties of materials Desarrollo de simulaciones de segundos principios dependientes del tiempo para el estudio de propiedades de transporte y ópticas en materiales |
| title |
Development of time-dependent second-principles simulations to study the transport and optical properties of materials |
| spellingShingle |
Development of time-dependent second-principles simulations to study the transport and optical properties of materials Fernández Ruiz, Toraya Charge transport Second principles model Localization Wannier functions Band disentanglement Fatbands Orbital character Transporte de carga Modelo de segundos principios Localización Funciones de Wannier Desentrelazamiento de bandas Fatbands Carácter orbital |
| title_short |
Development of time-dependent second-principles simulations to study the transport and optical properties of materials |
| title_full |
Development of time-dependent second-principles simulations to study the transport and optical properties of materials |
| title_fullStr |
Development of time-dependent second-principles simulations to study the transport and optical properties of materials |
| title_full_unstemmed |
Development of time-dependent second-principles simulations to study the transport and optical properties of materials |
| title_sort |
Development of time-dependent second-principles simulations to study the transport and optical properties of materials |
| dc.creator.none.fl_str_mv |
Fernández Ruiz, Toraya |
| author |
Fernández Ruiz, Toraya |
| author_facet |
Fernández Ruiz, Toraya |
| author_role |
author |
| dc.contributor.none.fl_str_mv |
García Fernández, Pablo (físico) Universidad de Cantabria |
| dc.subject.none.fl_str_mv |
Charge transport Second principles model Localization Wannier functions Band disentanglement Fatbands Orbital character Transporte de carga Modelo de segundos principios Localización Funciones de Wannier Desentrelazamiento de bandas Fatbands Carácter orbital |
| topic |
Charge transport Second principles model Localization Wannier functions Band disentanglement Fatbands Orbital character Transporte de carga Modelo de segundos principios Localización Funciones de Wannier Desentrelazamiento de bandas Fatbands Carácter orbital |
| description |
ABSTRACT: One of the most important properties of matter is its response to the application of external electric fields. The control of this phenomenon is is behind much of the current technology. A microscopic understanding of the mechanisms behind charge transport started with Drude at the beginning of the XX century who created an empirical model that is still widely used today, continued with the semiclassical theory of transport in the 30s that added a quantum-mechanical description to the movement of electrons in a material, and is currently an open line of research focused in graphene and other systems that display non-trivial topological band structures. In the last decades the advances in computation, using first principles methods such as density functional theory (dft), have allowed improving our understanding of the electronic structure of materials. However, the ability to study transport using these methods, as well as the effects of temperature is still very limited. In recent years a new family of techniques based on dft, known as second principles (sp), have been developed to solve these difficulties. Its practical application requires the construction of models (extension of tight binding models including one electron, electron-electron and electron-phonon interactions), written in a basis set of localized functions: The Wannier basis set. However, as introduced by Kohn in the 60s, the ground state of metallic systems (main conductors of the electric current) are characterized by a wavefunction highly delocalized, so the use of localized functions like Wannier orbitals for their description seems contraindicated. To further complicate the problem, bands in metals are strongly entangled and it will be necessary to isolate the key bands that describe the behaviour of the system around the Fermi energy. In this work we perform a computational study of elemental metallic and semiconducting struc tures. We analyze the wannierization problem of these systems. We try to study the chemical origin of their bands (orbital character) by the calculation of the fatbands associated to the Wan nier orbitals, in order to gain intuition that helps in model generation. Besides, we present a brief introduction in theory of transport and localization of the ground state. As technical results, we collect the basics of first and second principles, as well as the model generation program and the systematic procedure used for the calculation of the Wannier functions in this work. |
| publishDate |
2021 |
| dc.date.none.fl_str_mv |
2021 2021-07-06 |
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master thesis http://purl.org/coar/resource_type/c_bdcc NA http://purl.org/coar/version/c_be7fb7dd8ff6fe43 |
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info:eu-repo/semantics/masterThesis |
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masterThesis |
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http://hdl.handle.net/10902/25154 |
| url |
http://hdl.handle.net/10902/25154 |
| dc.language.none.fl_str_mv |
Inglés eng |
| language_invalid_str_mv |
Inglés |
| language |
eng |
| dc.rights.none.fl_str_mv |
open access http://purl.org/coar/access_right/c_abf2 Atribución-NoComercial-SinDerivadas 3.0 España http://creativecommons.org/licenses/by-nc-nd/3.0/es/ |
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info:eu-repo/semantics/openAccess |
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open access http://purl.org/coar/access_right/c_abf2 Atribución-NoComercial-SinDerivadas 3.0 España http://creativecommons.org/licenses/by-nc-nd/3.0/es/ |
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openAccess |
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reponame:UCrea Repositorio Abierto de la Universidad de Cantabria instname:Universidad de Cantabria (UC) |
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Universidad de Cantabria (UC) |
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UCrea Repositorio Abierto de la Universidad de Cantabria |
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UCrea Repositorio Abierto de la Universidad de Cantabria |
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Development of time-dependent second-principles simulations to study the transport and optical properties of materialsDesarrollo de simulaciones de segundos principios dependientes del tiempo para el estudio de propiedades de transporte y ópticas en materialesFernández Ruiz, TorayaCharge transportSecond principles modelLocalizationWannier functionsBand disentanglementFatbandsOrbital characterTransporte de cargaModelo de segundos principiosLocalizaciónFunciones de WannierDesentrelazamiento de bandasFatbandsCarácter orbitalABSTRACT: One of the most important properties of matter is its response to the application of external electric fields. The control of this phenomenon is is behind much of the current technology. A microscopic understanding of the mechanisms behind charge transport started with Drude at the beginning of the XX century who created an empirical model that is still widely used today, continued with the semiclassical theory of transport in the 30s that added a quantum-mechanical description to the movement of electrons in a material, and is currently an open line of research focused in graphene and other systems that display non-trivial topological band structures. In the last decades the advances in computation, using first principles methods such as density functional theory (dft), have allowed improving our understanding of the electronic structure of materials. However, the ability to study transport using these methods, as well as the effects of temperature is still very limited. In recent years a new family of techniques based on dft, known as second principles (sp), have been developed to solve these difficulties. Its practical application requires the construction of models (extension of tight binding models including one electron, electron-electron and electron-phonon interactions), written in a basis set of localized functions: The Wannier basis set. However, as introduced by Kohn in the 60s, the ground state of metallic systems (main conductors of the electric current) are characterized by a wavefunction highly delocalized, so the use of localized functions like Wannier orbitals for their description seems contraindicated. To further complicate the problem, bands in metals are strongly entangled and it will be necessary to isolate the key bands that describe the behaviour of the system around the Fermi energy. In this work we perform a computational study of elemental metallic and semiconducting struc tures. We analyze the wannierization problem of these systems. We try to study the chemical origin of their bands (orbital character) by the calculation of the fatbands associated to the Wan nier orbitals, in order to gain intuition that helps in model generation. Besides, we present a brief introduction in theory of transport and localization of the ground state. As technical results, we collect the basics of first and second principles, as well as the model generation program and the systematic procedure used for the calculation of the Wannier functions in this work.RESUMEN: Una de las propiedades más importantes de la materia es su respuesta a la aplicación de un campo eléctrico externo, cuyo control está detrás de gran parte de la tecnología actual. El estudio microscópico del transporte de carga comenzó con Drude a comienzos del siglo XX con un modelo totalmente empírico, ampliamente usado aún en la actualidad, continuó con la teoría semiclásica en los años 30, que añadió una descripción mecánico-cuántica al movimiento de electrones en un material, y sigue siendo un tema abierto de investigación en la actualidad, centrado en el grafeno y otros sistemas que muestran estructuras de bandas topológicas no triviales. En las últimas décadas los avances en compucación han permitido usando métodos de primeros principios como la dft, mejorar el estudio de la estructura electrónica de los materiales. Sin embargo, la capacidad de estudiar el transporte a través de estos métodos, así como los efectos de la temperatura o rupturas de simetría es todavía muy limitado. Para ello en los últimos años se están desarrollando una nueva familia de técnicas basadas en la dft, conocidos como segundos principios (sp) que pretenden resolver dichas dificultades. Su aplicación práctica requiere de la generación de modelos (extensiones de modelos tipo enlace fuerte que incluyen contribuciones a un electron, electrón-electrón y electrón-red), descritos en una base de funciones localizadas: la base de funciones de Wannier. Sin embargo, como ya introdujo Kohn en los 60s, el estado fundamental de los metales (principales conductores de la corriente eléctrica) se caracteriza por una función de onda muy deslocalizada, por lo que el uso de funciones localizadas, como los orbitales de Wannier para su descripción no parece adecuado. Para complicar aún más el problema, tenemos que las bandas de los metales están fuertemente entrelazadas y será necesario aislar las bandas clave que describen el comportamiento del sistema en torno a la energía de Fermi. En este trabajo se va a realizar un estudio computacional de metales y semiconductores elementales. Vamos a analizar el problema de la wannierización en dichos sistemas. Trataremos de estudiar el origen químico de sus bandas (carácter orbital) mendiante el cálculo de las fatbands de bandas de Wannier, para ganar intuición que ayude a la generación de modelos. Además, se platea una breve introducción de teoría del transporte y de la localización del estado fundamental. Como resultados técnicos, recogemos las nociones básicas de métodos de primeros y segundos principios, así como del programa generador de modelos y del procedimiento sistemático para obtener funciones de Wannier utilizado en el trabajo.Máster en Química Teórica y Modelización ComputacionalGarcía Fernández, Pablo (físico)Universidad de Cantabria20212021-07-06master thesishttp://purl.org/coar/resource_type/c_bdccNAhttp://purl.org/coar/version/c_be7fb7dd8ff6fe43info:eu-repo/semantics/masterThesishttp://hdl.handle.net/10902/25154reponame:UCrea Repositorio Abierto de la Universidad de Cantabriainstname:Universidad de Cantabria (UC)Inglésengopen accesshttp://purl.org/coar/access_right/c_abf2Atribución-NoComercial-SinDerivadas 3.0 Españahttp://creativecommons.org/licenses/by-nc-nd/3.0/es/info:eu-repo/semantics/openAccessoai:repositorio.unican.es:10902/251542026-06-02T12:39:31Z |
| score |
15,301603 |