Berlin 2012 – wissenschaftliches Programm

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MA: Fachverband Magnetismus

MA 3: Bio- and Molecular Magnetism

MA 3.9: Vortrag

Montag, 26. März 2012, 11:45–12:00, EB 202

Ab initio inspection of magnetic and redox bistability — •Mikaël Kepenekian — CIN2, Bellaterra, Spain

Molecular materials have stimulated intense experimental and theoretical work over the last decades. Indeed, the nature of these materials allows one to take advantage of the chemical engineering in order to design systems of interest. After achievements in the fields of magnetism and conduction, molecular materials are now sought as they can associate these properties. Nevertheless, the simulation of such materials remains a problem since (i) different energetic scales are involved, and (ii) the mono-reference nature of DFT-based calculations prevent from an accurate description of properties such as magnetism. In contrast, multi-reference wavefunction-based calculations offer the opportunity to work with proper spin-states, and give access to excited states. These methods have proven their ability to provide a quantitative agreement with experience, particularly in the field of molecular magnetism.

In this work, we used multi-reference ab initio calculations to investigate the microscopic origin of the behavior exhibited by bistable molecular materials. Starting from the inspection of spin-crossover complexes we were able not only to identify a microscopic origin of the spin-crossover phenomenon but also to quantify the magnitude of the hysteresis width. More sophisticated scenario involving the simultaneous spin and charge distribution change can also be anticipated in porphyrin-based system. At the molecular level, the requirements for bistability can be foreseen and specific target objects can be proposed in the light of the electronic and structural modifications.