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approvedextended_abstract.pdf2015-06-09 09:20:41Klaus-Dieter Bauer

Abstracts

Author: Klaus-Dieter Bauer
Requested Type: Either Oral or Poster
Submitted: 2015-05-24 09:12:26

Co-authors: M. Panholzer, K. Hingerl

Contact Info:
CDL-MS-MACH (Christian Doppler Laboratory for Micr
Altenberger Straße 69
Linz,   4040
Austria

Abstract Text:
For centrosymmetric crystals, bulk dipole contributions to second
harmonic generation (SHG) are symmetry-forbidden. At the surface on
the other hand the symmetry is broken and a dipolar SHG signal is
produced, allowing the use of SHG as a surface-sensitive probe.

However, literature also discusses a quadrupole contribution arising
from the bulk regime, which can be on the same order of magnitude as
the surface dipole contribution and thus are needed for modeling
experimental results. In existing ab-initio calculations of the second
order optical susceptibility, however, the long-wavelength limit is
taken rigorously.

In order to obtain the bulk quadrupole contribution, we need to
consider a first-order correction to the long-wavelength limit. We can express this correction as first order expansion of the
microscopic response function in the wave vector arguments and now
persue evaluation of these expressions with DFT, initially in the
framework of the independent particle approximation.

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