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Ab initio model potential embedded cluster calculations including lattice relaxation and polarization: Local distortions on Mn(2+)-doped CaF2

Authors
Journal
The Journal of Chemical Physics
0021-9606
Publisher
American Institute of Physics
Publication Date
Keywords
  • Química Cuántica
  • Espectroscopía
Disciplines
  • Chemistry
  • Mathematics
  • Physics

Abstract

Ab initio model potential embedded clusternullnullcalculations including lattice relaxation and polarization: Localnullnulldistortions on Mn2+-doped CaF2 u a f n ti ir e n o 4 e t I that these experiments are expensive and far from routinary, as well as to the large uncertainties that sometimes accom- pany the result,1 the measurements being restricted to the ground state geometries. Trying to overcome these difficul- ties, other more conventional experimental information, such as EPR spectra and zero-phonon absorption/emission lines, have been used in order to indirectly deduce the distance between the impurity and its first neighbors;2 in this case, the gathered information is limited to a single distance corre- sponding to the impurity ground state on a highly symmetric site. On the other hand, the long developments in quantum chemistry led, in the field of isolated molecules, to very ef- ficient theoretical methods able to provide accurate quantita- tive geometries for the ground and excited molecular states, no matter how complicated they are. In these circumstances, the accepted importance of a close collaboration between theory and experimentation in order to facilitate new achievements in the field of doped materials,3 becomes ex- ceptionally clear. From the theoretical point of view, the cluster approximation4 proved itself to be a very fruitful tool, and the last years witnessed a series of developments in embed- ded cluster approaches. In the case of ionic crystals, the initio model potential embedding method5,14 ~AIMP!, which is a practical implementation of the group function theory developed by McWeeny15 and Huzinaga,16 translates to the field of ionic crystals the experience gathered in effective core potential molecular calculations.17 According to the AIMP embedded cluster method, model potentials represent- ing complete cations and complete anions from an ionic lat- tice are calculated and straightforwardly added to the one- electron contribution to the Ha

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