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).

      Abstract:

      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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