Project

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Accurate and efficient electronic-structure functionals for energies and spectra of materials

Applicant Marzari Nicola
Number 179138
Funding scheme Project funding
Research institution Laboratoire de théorie et simulation des matériaux EPFL - STI - IMX - THEOS
Institution of higher education EPF Lausanne - EPFL
Main discipline Material Sciences
Start/End 01.04.2018 - 30.09.2022
Approved amount 908'068.00
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All Disciplines (2)

Discipline
Material Sciences
Condensed Matter Physics

Keywords (14)

computational materials science; first-principles simulations; density-functional theory; first-principles spectroscopies; Hubbard functionals; Koopmans functionals; self-interaction corrections; electronic and optical properties; band gaps; correlated materials; Li-ion batteries; solid-state conductors; photocatalytic water splitting; layered materials

Lay Summary (Italian)

Lead
Le simulazioni al calcolatore permetto di predire le proprietà di nuovi materiali prima ancora di dover fare un esperimento. Queste simulazioni sono basate sulle equazioni fondamentali della meccanica quantistica (per questo si chiamano da principi primi), ma a causa della loro complessità possono essere risolte solo con alcune approssimazioni. Questo progetto si occupa di sviluppare nuovi metodi che siano in grado di predirre con più precisione le proprietà elettroniche ed ottiche di nuovi materiali, per poter applicare le simulazioni da principi primi al campo delle energie rinnovabili: ad esempio per trasformare la luce del sole in combustibili puliti, e per scoprire materiali per le batterie al litio che le rendano più sicure e più durevoli.
Lay summary

Soggetto e obiettivo

L'obiettivo di questo progetto è  di rendere le simulazioni da principi primi più accurate e più efficienti nel predire le proprietà elettroniche ed ottiche di nuovi materiali. Per fare questo stiamo sviluppando delle estensioni della teoria del funzionale densità (premio Nobel del 1998 a Walter Kohn) per poter descrivere con accuratezza i processi di trasferimento di carica - dove un elettrone si trasferisce all'interno di un materiale (ad esempio da un atomo di litio ad un atomo di cobalto, in una batteria al litio) o viene estratto completamente (ad esempio nei sistemi fotovoltaici e nei processi di fotocatalisi, dove la luce del sole viene trasformata in una corrente elettrica o promuove una reazione chimica).

Contesto socio-scientifico

Poter simulare con accuratezza ed efficienza queste proprietà ci permetterà di esplorare molto rapidamente nuove combinazioni di materiali, e di farlo molto più velocemente di quanto si potrebbe fare in un esperimento. In questa prospettiva, diventa fondamentale che le simulazioni siano sufficientemente precise nel descrivere le proprietà che si vogliono descrivere. Grazie ai metodi che verranno sviluppati in questo progetto diventerà possibile poter studiare con grande rapidità ed accuratezza i materiali complessi che vorremmo sviluppare per moltissime applicazioni nel campo delle energie rinnovabili. 


Direct link to Lay Summary Last update: 30.03.2018

Responsible applicant and co-applicants

Employees

Associated projects

Number Title Start Funding scheme
189924 Hydronics 01.06.2020 Sinergia

Abstract

Background and rationale of the project: Electronic-structure simulations are having a transformational role in science and engineering, spanning fields that go from condensed-matter physics to chemistry, materials science, chemical and mechanical engineering, and earth sciences, to name just a few. At the core of this transformational role has been the accuracy and efficiency of density-functional theory, coupled with the broad availability of robust computational codes that implement and make available to the community at large core or advanced functionalities. This accuracy and efficiency has nowadays reached the point where high-throughput simulations can routinely be employed to screen thousands of materials for optimal properties or performance. Nevertheless, and notwithstanding these successes, crucial limitations remain, and hinder accurate and efficient simulations on many materials or properties of fundamental importance for current scientific and technological applications, from energy harvesting and storage to quantum technologies. Some of these limitations are related to the accuracy of current approximations to the unknown exchange-correlation functional, while others are intrinsic to the theory itself, that, as a static functional of the local charge density, can only describe exactly (if the exact functional were known) the total energy of a system and its derivatives, precluding any access to spectroscopic information, except, at least in principle, the position of the highest occupied orbital.Overall objectives and specific aims: This research proposal aims 1) at the development, implementation, and dissemination in open-source codes of extended Hubbard functionals able to describe correctly the electronic-structure of key functional materials, such as mixed-valence oxides; 2) at the development, implementation, and dissemination of spectral functionals, such as Koopmans-compliant functionals, able to describe the spectroscopic properties of molecules and materials; and 3) at the validation and application of these advances to pressing problems in fundamental or applied materials science, chosen for their relevance as paradigmatic case studies. The project is organized into three workpackages, where researchers are coupled between development and application efforts: i) development and dissemination of extended, screened Hubbard functionals including intersite couplings; ii) development and dissemination of spectral Koopmans functionals; iii) application to core materials' projects, covering Li-ion cathode materials during charge and discharge, the structure and electronic-structure of rare-earth nickelates, and layered, exfoliable materials for photocatalytic water splitting. All applications involve collaborations with experimental partners.Methods to be used: While the advances described above are general to density-functional theory and some of its extensions, and thus open to be implemented in the many codes available today, they will be implemented and disseminated by us into the widely used open-source code Quantum ESPRESSO, connecting thus naturally to a large community of users (Web of Science records 1245 papers published in 2016, making it the most used open-source code for quantum simulations of materials). A core underlying theme will be the use of linear-response techniques based on density-functional perturbation theory, to make the calculation of the screening/gauge parameters automatic, robust, and efficient: the Hubbard on-site U and inter-site V parameters will be calculated automatically, and without the need to resort to expensive supercells' calculations, as will be the screening parameters of Koopmans-compliant functionals. The importance of this effort should not be underestimated, notwithstanding the priority of the scientific goals (i.e.~of having functionals able to descrive difficult materials or novel properties): by providing reliable and robust protocols for the determination of these quantities, and verified and validated codes that can exploit the power of these functionals, these developments become part of a true ``open science'' portfolio of community tools.Expected results and their impact: First and foremost, the developments described above would bring accuracy and efficiency to the study of the electronic structure of complex materials, with functionals tuned to the response functions of the system at hand, bypassing the need of more expensive (and somehow less satisfactory) hybrid functionals, with also the capability to describe spectroscopic properties (remarkably, the performance of Koopmans' functionals is comparable or even slightly superior to the state-of-the-art in diagrammatic techniques, a much more involved and computationally expensive effort). The applications chosen highlight the shortcomings of current approaches, and hint at the vast class of functional materials that could be addressed with such techniques. Last, the spectral formulation point to an evolution of the field towards functional theories of more complex quantities than the charge density, and hence at the capability of delivering more complex properties than the total energy.
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