Electric Field Control of Spin States in Trigonal Two-Electron Quantum Dot Arrays and Mixed-Valence Molecules: II. Vibronic Problem

In this article, the vibronic model for an electric field switchable mixed-valence trimer containing two delocalized electrons or holes is proposed and examined. The role of the vibronic coupling on the electric field effects is analyzed by means of the semiclassical adiabatic approach and, alternatively, with the aid of the numerical analysis of the Schrodinger equation with due allowance for the kinetic energy of the ions (dynamic problem). The adiabatic potential landscapes have been calculated by taking into account the influence of the electric field. As the adiabatic approximation has a limited frame of validity, the study of the electric field effects has also been performed within more rigorous quantum mechanical evaluation of the energy levels arising in the combined Jahn-Teller/pseudo-Jahn-Teller two-mode three-level vibronic problem. The vibronic coupling gives rise to a significant effect on the energies of spin levels and charge distributions, considerably facilitating the conditions for the field-induced spin-switching. On the basis of this analysis of the electronic and vibronic states, the criteria for rational design of molecular spin-switching devices are suggested.