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SUMMARY:Grain boundaries in strontium titanate - Prof. Mike Finnis\, Imper
 ial College London
DTSTART:20080214T141500Z
DTEND:20080214T151500Z
UID:TALK9315@talks.cam.ac.uk
CONTACT:Dr Jonathan Keeling
DESCRIPTION:I will describe some recent work  on grain boundaries in stron
 tium titanate\, illustrating concepts that have wider implications. Densit
 y functional calculations will be compared with classical models in some v
 ery simple cases of symmetric (111) and (112) boundaries. I will discuss t
 he concept of ionic charges with reference to calculated Born effective ch
 arges (the only uniquely defined charges on ions) and Mulliken charges. Fi
 nally\, (most of the talk) I will explain how the mathematical machinery o
 f quaternions is a simple and natural way to extract the best estimate of 
 grain boundary orientations from experimental electron diffraction data.\n
LOCATION:TCM Seminar Room\, Cavendish Laboratory
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