Reference : UMR5626-TROSAU-006
Nombre de Postes : 1
Workplace : TOULOUSE
Date of publication : Monday, January 23, 2023
Scientific Responsible name : Trond SAUE
Type of Contract : PhD Student contract / Thesis offer
Contract Period : 36 months
Start date of the thesis : 20 March 2023
Proportion of work : Full time
Remuneration : 2135 euros gross/month
Description of the thesis topic
** Highly accurate relativistic calculations of molecular properties **
The PhD project is part of the project HAMP-vQED [Highly Accurate Molecular Properties using variational Quantum Electrodynamics] funded by an ERC Advanced Grant.
Background : The building blocks of chemistry are organized in the periodic table, which requires quantum mechanics for its understanding. In the 1980s it was realized that in order to correctly describe the heavy elements in the lower part of the periodic table, the special theory of relativity had to be invoked. Does chemistry need more physics ? The HAMP-vQED project will investigate the possible role of quantum electrodynamics (QED) in chemistry. It will provide a protocol for highly accurate calculations of molecular properties, with particular attention to properties that probe the electron density in the close vicinity of atomic nuclei, where the QED-effects are created. The HAMP-vQED project adheres to the general framework of quantum chemistry by seeking a variational (non-perturbative) approach using local (Gaussian) basis functions.
Content: The sophisticated machinery of QED, built on perturbation theory and the iconic Feynman diagrams, can only be applied to few-electron systems
For general heavy atoms or molecules some progress has been made using effective QED potentials [1-4]. We have recently reported the implementation of three effective QED potentials in the DIRAC code for molcular calculations , whereas a complementary implementation has been reported (also in DIRAC) by Skripnikov . The present thesis concerns the calculation of core properties (hyperfine interaction,
g-tensor, paramagnetic NMR parameter) of open-shell molecules, at the coupled cluster level, using such effective QED-potentials. A significant part of the thesis concerns the formulation and implementation of the appropriate methodology for such calculations.
1. E.A. Uehling, “Polarization Effects in the Positron Theory”, Phys. Rev. 48, 55–63 (1935)
2. P. Pyykkö and U. B. Zhao, “Search for effective local model potentials for simulation of quantum electrodynamic effects in relativistic calculations”, J. Phys. B: At. Mol. Opt. Phys. 36, 1469 (2003)
3. V.V. Flambaum and J. S. M. Ginges, “Radiative potential and calculations of QED radiative corrections to energy levels and electromagnetic amplitudes in many-electron atoms”, Phys. Rev. A 72, 052115 (2005).
4. V.M. Shabaev, I. I. Tupitsyn, and V. A. Yerokhin, “Model operator approach to the Lamb shift calculations in relativistic many-electron atoms”, Phys. Rev. A 88, 012513 (2013)
5. Ayaki Sunaga, Maen Salman and Trond Saue, J. Chem. Phys. 157, 164101 (2022)
6. L. V. Skripnikov, The Journal of Chemical Physics 154, 201101 (2021).
The thesis requires a candidate,trained in theoretical physics or chemistry, with a solid background in mathematics and ready to invest effort in modelling and programming.
The candidate should provide the following documents:
2) Letter of motivation
3) Letter of recommendation (with ranking). As for the ranking, we would like your reference to make a judgement on how you place in relation to the other students having done the same Master programme. E.g. are you in the top 10% or top 25 % etc. This is just indicative, and the admissions committee will focus mostly on the text of your motivation letter and CV rather than the % ranking.
The Laboratoire de Chimie et Physique Quantiques (LCPQ) is an academic joint research unit (UMR 5626) between University Toulouse III and CNRS (Chemistry institute as first affiliation, Physics institute as second affiliation). Its current contours date back to January 2007.
The LCPQ is currently involved in various domains of theoretical chemistry (mainly quantum chemistry) and theoretical molecular physics, and at their interface. It has a strong methodological component, that allows for the development of several computational codes, as well as teams involved in the application of all types of methods to systems of physico-chemical and biological interest: molecular magnetism, high-resolution spectroscopy, reactivity and photochemistry of coordination complexes and biomolecules, aggregates and nanoparticles.
The laboratory is organised in four teams:
- Theory (THEO)
- Theoretical and Computational Photochemistry (PTC)
- Extended Systems and Magnetism (SEM)
- Modelisation, Clusters, Dynamics (MAD)
The selected candidate will join the THEO team.
Constraints and risks
Nothing to report
HAMP-vQED [Highly Accurate Molecular Properties using variational Quantum Electrodynamics]
Does chemistry need more physics? It has long been known that the construction of the periodic table of elements is explained by quantum mechanics, and that relativity must be added to properly describe the chemistry of heavy elements. The HAMP-vQED project aims at probing the role of quantum electrodynamics (QED) in chemistry by providing an approach that allows for the accurate calculation of molecular properties, with a particular focus on those that probe the electron density close to the atomic nuclei where QED effects are created. The proposed approach fits into the usual framework of quantum chemistry, namely a variational approach using local basis functions.
For more information: https://dirac.ups-tlse.fr/hamp-vqed/doku.php
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