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SM ISO690:2012 TSUKERBLAT, Boris; PALII, Andrew; CLEMENTEJUAN, Juan; CORONADO, Eugenio. Symmetry assisted approach to the nonadiabatic vibronic problem: advances and challenges . In: Materials Science and Condensed Matter Physics. Editia a 7a, 1619 septembrie 2014, Chișinău. Chișinău, Republica Moldova: Institutul de Fizică Aplicată, 2014, p. 30. 
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Materials Science and Condensed Matter Physics Editia a 7a, 2014 

Conferința "Materials Science and Condensed Matter Physics" Chișinău, Moldova, 1619 septembrie 2014  


Pag. 3030  


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In context of the presentday trends in the studies of the nanosized systems which are at the border between classical and quantum scales here we present a symmetry assisted approach aimed to the accurate solution of the nonadiabatic vibronic JahnTeller (JT) problem in large scale multimode systems, like impurity centers and clusters in crystals, molecular and biological objects, etc. For the systems at nanoscale the classical approaches fails meanwhile within the quantummechanical treatment we face a very high dimension of the Hilbert space aggravated by a poor convergence of the computational procedure with the truncated electronvibrational basis. The system under consideration is supposed to consist of the set of the electronic levels of definite symmetries mixed by the active JT vibrational modes. The proposed algorithm for the solution of the JT problem takes full advantage from the point symmetry arguments. We develop a special algorithm for the design of the symmetry adapted electronvibrational basis with the aid of the subsequent application of the special operators (which we call multivibronic operators) based on the subsequent multiple ClebschGordan coupling with the GramSchmidt orthogonalization of the basis at each step [1] of the procedure. Finally, the generated vibrational basis is coupled to the electronic ones to get the symmetry adapted basis in which the full matrix of the JT Hamiltonian blocked to the maximum extent. The general approach is applied to the evaluation of the hybrid electronvibrational states and intervalence optical absorption in mixed valence systems containing arbitrary number of the localized spins and itinerant electrons. In particular, we discuss [2,3] the intriguing magnetic properties of the 2ereduced MV dodecanuclear Keggin anion in which the electronic pair is delocalized over twelve sites (Td) giving rise to the (1T2+1E+1A1) (e+t2) (3T1+3T2) (e+t2) combined JT/pseudo JT problems for the spinsinglet and spintriplet states. We report also the evaluation of the charge distribution and electronic and vibronic levels of mixedvalence tetraruthenium systems assembled as two coupled CreutzTaube complexes for which the pioneering concept (exploration of bistable charge distribution rather than qubits) of implementations as molecular quantumdot cellular automata was recently proposed and widely discussed. The financial support of the Israel Science Foundation is gratefully acknowledged (ISF, grant no. 168/09). 

