Presentation

L’IRSAMC (The Institute of Research on Complex Atomic and Molecular Systems) is a federation of four laboratories (LCAR, LCPQ, LPCNO, LPT), in physics and fundamental chemistry whose research activities are supported both by the Université Paul Sabatier, the CNRS and INSA

Publications of 4 research laboratories

  • Hal-LCAR. - Laboratory Collisions Clusters Reactivity, from 1990 until todays
  • Hal-LCPQ. - Quantum Chemistry and Physics Laboratory, from 2007 until todays
  • Hal-LPCNO. - Physics and Chemistry of Nano Objects Laboratory, from 2006 until todays
  • Hal-LPT.- Theoretical Physics Laboratory, from 2003 until todays

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[tel-02316080] Utilization of renormalized mean-field theory upon novel quantum materials  (16/10/2019)  
This thesis is aiming in utilizing the strongly correlated t-J Hamiltonian for better understanding the microscopic pictures of certain condensed matter scenario. One of the long existing issues in the Hubbard model and its extreme version, t-J model, lies in the fact that there is not an analytical way of solving them. Therefore, when dealing with these models, numerical approaches become very crucial. In this thesis, we will present one of the methods called renormalized mean-field theory (RMFT) and exploit it upon the t-J model. Thanks to the concept proposed by Gutzwiller, all we have to do is to try to include the correlation of electrons, which is mainly the most difficult part, with several renormalization factors. After obtaining the correct form of these factors, we can apply the routine mean-field theory in solving for the Hamiltonian, which is the principle methodology throughout this thesis. Next, the physical systems that we are interested in consist of two parts. The mystery of High-Tc superconductivity comes first. After 30 years of its discovery, people still cannot settle down a complete microscopic theory in describing this exotic phenomenon. However, with more and more experimental equipment with higher accuracy nowadays, lots of behavior of copperoxide superconductor (also known as cuprate) have been revealed. Those discoveries can definitely help us better understand its microscopic mechanism. Therefore, from the theoretical side, to compare the calculated data with experiments leads us to know whether our theory is on the right track or not. We have produced tons of data and made a decent comparison which will be shown in the main text. The second system we are curious about is the mechanism of electrons under magnetic field. The Hofstadter butterfly along with its Hamiltonian, the Harper-Hofstadter model has achieved great success in describing free electrons' movement with lattice present. Thus, it will be also interesting to ask the question: what will happen if the electrons are correlated. Our RMFT for t-J Hamiltonian, by adding an additional phase in the hopping term, happens to serve as a great preliminary model for answering this question. We will compare the results of ours with our collaborators, who solved this model by a different approach, the exact diagonalization(ED). Together with our calculations, we proposed several discoveries which might be realized by the cold atom experiments in the future.

[hal-02310866] Using Density Functional Theory Based Methods to Investigate the Photophysics of Polycyclic Aromatic Hydrocarbon Radical Cations: A Benchmark Study on Naphthalene, Pyrene and Perylene Cations  (11/10/2019)  
[hal-02310251] Single-site cobalt and zinc catalysts for the ring-opening polymerization of lactide  (11/10/2019)  
[hal-02309051] Gravitational phase transitions and instabilities of self-gravitating fermions in general relativity  (16/10/2019)  
[hal-02309050] Caloric curves of classical self-gravitating systems in general relativity  (16/10/2019)  

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