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Reference : UMR5626-PIELOO-002
Workplace : TOULOUSE
Date of publication : Tuesday, March 10, 2020
Scientific Responsible name : Pierre-Francois Loos
Type of Contract : PhD Student contract / Thesis offer
Contract Period : 36 months
Start date of the thesis : 1 October 2020
Proportion of work : Full time
Remuneration : 2 135,00 € gross monthly
Description of the thesis topic
Processes related to electronically excited states are central in chem- istry, physics, and biology, playing a key role in ubiquitous processes such as photochemistry, catalysis, and solar cell technology. However, defining an effective method that reliably provides accurate excited-state energies remains a major challenge in theoretical chemistry. In this project, the PhD student will aim at developing a totally novel approach to obtain excited-state energies and wave functions in molecular systems thanks to the properties of non-Hermitian Hamiltonians. The key idea is to perform an analytic continuation of conventional computational chemistry meth- ods. Indeed, through the complex plane, ground and excited states can be naturally connected . In a non-Hermitian complex picture, the energy levels are sheets of a more complicated topological manifold called Rie- mann surface and they are smooth and continuous analytic continuation of one another.
The main goal of this project is to develop a new theoretical approach allowing to connect, through the complex plane, electronic states. Instead of Hermitian Hamiltonians, we propose to use a more general class of Hamiltonians which have the property of being P T -symmetric, i.e., invariant with respect to combined parity reflection P and time reversal T [2, 3]. This weaker condition ensures a real energy spectrum in unbroken PT -symmetric regions. PT -symmetric Hamiltonians can be seen as analytic continuation of conventional Hermitian Hamiltonians. Using P T -symmetric quantum theory, an Hermitian Hamiltonian can be analytically continued into the complex plane, becoming non-Hermitian in the process and exposing the fundamental topology of eigenstates. Our gateway between ground and excited states are provided by exceptional points which lie at the boundary between broken and unbroken P T -symmetric regions.
The present postdoctoral position is funded through the ERC CoG H2020 (project PTEROSOR 863481).
The Laboratoire de Chimie et Physique Quantiques (LCPQ) UMR5626 in Toulouse (Universite Paul Sabatier) is part of the IRSAMC (physics) institute and is located on the campus og the Universite Paul Sabatier.
The LCPQ gathers more than 20 permanent researchers working on various areas of computational and theoretical chemsitry.
Constraints and risks
Le poste postdoctoral actuel est financé par l'ERC CoG H2020 (projet PTEROSOR 863481).
Le projet vise à développer une approche totalement nouvelle pour obtenir des énergies à l'état excité et des fonctions d'onde dans les systèmes moléculaires grâce aux propriétés des hamiltoniens non hermitiens et PT-symétriques.
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