PhD n°3
Eligibility:
EU mobility rules apply. In principle, applicants can have any nationality and any current residence (although immigration rules apply, favoring
EU applicants). Candidates who have already been awarded a PhD degree are not eligible. In addition, candidates who have already spent more than 12 months in the Belgium within the last 3 years are not eligible (unless as part of a procedure for obtaining refugee status under the Geneva Convention).
Objectives:
Experiments are now so precise that they challenge static and idealized theories. We will push the limits of spectroscopic simulations with realistic materials models. The central challenges today are to include a material’s environment and disorder, whether thermal, chemical or structural. As full ab initio calculations are very heavy, either with explicit supercells or perturbation theory, we will “machine learn” 1) intermediate quantities such as mean square displacements and 2) the final shifts and linewidths of the spectrum, from a limited set of data points.
- Include thermal and chemical disorder effects in Xray and Transmission Electron Microscopy (TEM) simulations (in particular holography…). Train ML models to add these effects to “bare” calculations, based on chemistry and structure
- Develop a general theoretical framework for coherent (e.g., phonons, controlled doping) and incoherent (temperature, random alloying, vacancies…) perturbations in photon and electron spectroscopies.
- Applications to 2D materials and surfaces, including magnetic systems, e.g., CrI3, transition metals, and chalcogenides.
Expected Results:
- Machine learning algorithm for the vibrational mean square displacement (MSQD) and other thermodynamic quantities, based on existing databases, ab initio MD, and NN potentials (with MLU, WP2)
- Extension to anharmonic lattice dynamics using the Temperature Dependent Effective Potential method (WP1)
- Comparison of the Coherent Potential Approximation (CPA) and Molecular Dynamics, and development of perturbation theory schemes beyond the Debye Waller approximation (WP1,3)
- Inclusion of vibrational and thermal effects in X-ray spectroscopies and TEM (WP1, WP3):
- Anisotropic/anharmonic MSQD as input for the CPA KKR (with UWB) in complex materials, surfaces and interfaces.
- Realistic prediction of STEM maps with a dynamical and/or thermalised electron potential (with DrProbe or QSTEM).
Planned secondment(s): 6 months
- Intersectoral: TME: Hannah Johnson M18-M20; investigate the vibrational and thermal properties of MoSx matrices for Hydrogen Evolution Reaction catalysis
- MLU: M Marques, M12-14; to integrate ML tools for environmental (in particular vibrational) effects on spectroscopy
Enrolment in Doctoral degree(s):
Université de Liège
Contact:
matthieu verstraete
Matthieu.Verstraete@uliege.be