Communication: Novel quantum states of electron spins in polycarbenes from ab initio density matrix renormalization group calculations

Wataru Mizukami, Yuki Kurashige, Takeshi Yanai

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30 Citations (Scopus)


An investigation into spin structures of poly(m -phenylenecarbene), a prototype of magnetic organic molecules, is presented using the ab initio density matrix renormalization group method. It is revealed by achieving large-scale multireference calculations that the energy differences between high-spin and low-spin states (spin-gaps) of polycarbenes decrease with increasing the number of carbene sites. This size-dependency of the spin-gaps strikingly contradicts the predictions with single-reference methods including density functional theory. The wave function analysis shows that the low-spin states are beyond the classical spin picture, namely, much of multireference character, and thus are manifested as strongly correlated quantum states. The size dependence of the spin-gaps involves an odd-even oscillation, which cannot be explained by the integer-spin Heisenberg model with a single magnetic-coupling constant.

Original languageEnglish
Article number091101
JournalJournal of Chemical Physics
Issue number9
Publication statusPublished - Sep 7 2010


All Science Journal Classification (ASJC) codes

  • Physics and Astronomy(all)
  • Physical and Theoretical Chemistry

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