Simil Thomas, S. Ramasesha, Karen Hallberg, Daniel Garcia
We study low-lying correlated electronic states of fused azulenes using the long-range interacting Pariser-Parr-Pople model and the finite density matrix renormalization group method. The ground state is a singlet for oligomers with up to 5 azulene units. For oligomers with more than 5 azulene units and beyond 6 azulene units the oligomers have a triplet ground state. From the excitation gaps between the lowest Ms=0 state and the lowest states in Ms=1,2 and 3 sector we predict that the ground state spin of the fused azulene increases with number of azulene units. In the thermodynamic limit we expect the fused azulene to be a ferromagnet. Charge density calculations show that the ground state of the system has ferroelectric alignment of the dipoles of the monomeric units. Thus, a fused azulene system could be the first example of a molecule which is both ferromagnetic and ferroelectric in the ground state.
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http://arxiv.org/abs/1111.6720
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