Richard Jarman - Theoretical Study of the Nonlinear Optical Properties of KTiOPO4: an Extended Huckel/Sum-Over-States Approach

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      Publication Details (including relevant citation   information):

      Theoretical   Study of the Nonlinear Optical Properties of KTiOPO4:   an Extended Huckel/Sum-Over-States Approach, M. Munowitz, R.H.   Jarman and J.F. Harrison, Chem. Mater., 4, 1296 (1992).


      We investigate, within the framework of extended Huckel theory,   the origins and structural dependences

      of the electronic hyperpolarizability tensors of asymmetric TiO2   and TiO68-. The TiO68- species, which

      is a basic structural unit of KTiOPO4 (KTP), is taken as a   distorted octahedron with the trans oxygens

      placed asymmetrically above and below the TiO4 equatorial plane.   A term-by-term analysis of the per-

      turbative series for both TiO2 and TiO68- shows that second   harmonic generation derives predominantly

      from A excitations (relative to the asymmetric O-Ti-O axis) and   that the net hyperpolarizability results

      from the near cancellation of large contributions with opposite   signs. Specific contributions to the hy-

      perpolarizability, which we classify into three major     π families and three major σ  families, typically pass

      through minima and maxima as the difference between long and   short Ti-O bonds is increased.

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