Regensburg 2004 – scientific programme
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O: Oberflächenphysik
O 44: Elektronische Struktur (Experiment und Theorie) III
O 44.7: Talk
Friday, March 12, 2004, 12:45–13:00, H38
Second Harmonic Generation on NiO — •Georgios Lefkidis, Khompat Satitkovitchai, and Wolfgang Hübner — TU Kaiserslautern, PO Box 3409, D-67653, Germany
The second order susceptibility tensors, which are important for Optical Second Harmonic Generation (SHG) are studied for NiO starting from ab-initio calculations. To represent the (001) surface of the rocksalt NiO lattice we embed a NiO5−8 cluster in a charge point field which accounts for the Madelung potential due to the neighboring ions. Similarly, an embedded NiO6−10 cluster is used to represent the bulk. The quantum chemical calculation is performed at various levels, where the effect of the basis set is studied, and the energy correction due to electron correlations. A Complete Active Space Configuration Interaction is performed, while the excited states are studied with Single Excitation Configuration Interaction (CIS) with energy contribution from double and triple excitations. The electric and magnetic dipole transitions are used to calculate the χeee(2ω) and χmee(2ω) tensors.
While inversion symmetry of the bcc lattice leads to zero tensor elements for the bulk, the breaking of the symmetry on the surface gives non-zero elements within the electric-dipole approximation. On the other hand some χmee(2ω) elements exist for both bulk and surface. The effect of spin-orbit coupling on both tensors is discussed.