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Reference : UMR5493-CAMSER-004
Workplace : GRENOBLE
Date of publication : Thursday, January 30, 2020
Type of Contract : FTC Scientist
Contract Period : 12 months
Expected date of employment : 1 April 2020
Proportion of work : Full time
Remuneration : 2700€
Desired level of education : PhD
Experience required : Indifferent
Path integral computations of transport properties in solids
About 40 years ago, the path integral formulation of quantum mechanics due to Feynman was turned into a very efficient scheme for simulating numerically quantum systems at finite temperature. In this scheme, every quantum particle is represented as a ring polymercomposed of P “beads” connected by “springs” of stiffness 2π√P/(βh). The mapping becomes exact in the limit of a large number of beads. The system of ring polymers can be simulated using classical Monte Carlo or Molecular dynamics methods, and the sampling of its phase space gives a relatively straighJorward access to all thermodynamic properties ofthe quantum system at finite temperature.
The determination of transport properties (e.g. diffusion, heat or electrical conductivity) is much more tricky. Indeed, transport coefficients are determined by time dependent correlation functions, which are not directly accessible within the mapping described above.
However, correlation functions can be obtained in imaginary time using the path integral method. The imaginary time correlation function can then be transformed to real time, however this transformation requires computations with a very good accuracy.
The “Heatflow” project supported by ANR involves three scientists based in Grenoble (Jean-Louis Barrat, Markus Holzmann, Stefano Mossa) and will attempt to carry out this program for calculating heat conductivity of solids. Although it is well known that quantum effects are important for thermal properties even at intermediate temperature, no exact scheme is presently available to compute them for insulating solids. Such an exact scheme would allow one to investigate long standing problems such as the thermal anomalies of amorphous solids at low temperature, and be of technological importance for example for thermoelectric materials.
Within this project, the successful applicant will work together with three senior sciantists on the development of path integral computations on simple model solids, and its application to the computation of heat conductivity in crystals and disordered systems.
Very good theoretical background. Good analytical skills and interest in
numerical computations; interest in statistical physics, quantum
mechanics and materials science.
The LPMMC is a joint research unit in physics regrouping diverse theoretical competences under supervision of the Université Grenoble Alpes (UGA) and of the Centre National de la Recherche Scientifique (CNRS). The laboratory was first dedicated to numerical physics, it is now mainly oriented towards condensed matter and quantum physics.
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