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SUMMARY:Simulating STEM images - can we see bonds? - Jonathan Yates ( Depa
 rtment of Materials\, University of Oxford)
DTSTART:20200305T150000Z
DTEND:20200305T160000Z
UID:TALK134773@talks.cam.ac.uk
CONTACT:Yonatan Calahorra
DESCRIPTION:The electron charge density is of fundamental importance to th
 e physics of materials. It is the redistribution of electrons that occurs 
 when atoms bond which distinguishes materials from collections of independ
 ent atoms. It is also the case that the ground state properties of any mat
 erial system can be determined from the electron charge density. This is t
 he basis of Density Functional Theory (DFT)\, the most widely used and suc
 cessful technique for modelling materials at the atomic scale. While DFT h
 as been hugely successful as a tool for modeling materials systems quantum
  mechanically\, the approximations used to make such calculations practica
 l mean that there remains an important role for experiments to verify and 
 inform DFT results.\n I will first share some recent advances which improv
 e the predictive power of DFT calculations. I will then show how phase ima
 ging in the electron microscopy is sensitive to the effect of charge redis
 tribution from bonding. In particular how electron ptychography\, performe
 d in the STEM microscope\, provides the necessary sensitivity to detect th
 is subtle effect by directly imaging the charge redistribution. This provi
 des direct comparison to the charge density predicted by DFT simulations.
LOCATION:Goldsmiths 1\, Lecture Theatre\, Department of Materials Science 
 &amp\; Metallurgy
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