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DTSTAMP:20241213T132951Z
DTSTART:20241218T171500
DTEND:20241218T183000
SUMMARY:UniSysCat - Colloquium
DESCRIPTION:High multiplicity states in amorphous carbon and spin catalysis\nProf. Dr. Oleksiy Khavryuchenko\nShupyk National Healthcare University of Ukraine and NVision Imaging Technologies GmbH, Germany\nAbsolute majority of carbon materials have undefined local structure, varying from highly-defective micro-crystalline to completely amorphous. True amorphous ones, i.e. having no translational symmetry even on sub-nanoscale level, are the most enigmatic of them. Ultra-pure poly-phenol-formaldehyde-derived carbon samples were synthesized and examined by EPR. In order to explain their physical (optical, mechanical and magnetic) and chemical properties we have elaborated a 'two-domain' model, comprising 1) curved graphene sheets and 2) short chains of carbene atoms, connecting them. Model carbon nanoparticles representative of the graphene-like and amorphous domains of active carbon are investigated with density-functional theory (DFT), time-dependent DFT (TDDFT), and complete active space self-consistent field (CASSCF) with n-electron valence state perturbation theory (NEVPT2) methods, exhibiting a variety of local structures with different chemical, optical and magnetic properties. Interplay between singlet and triplet states in large models and its effect on chemistry of true amorphous carbon and use as a spin catalyst is discussed, along with limitations and perspectives of computational approaches in carbon chemistry.
LOCATION:C 264
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