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SUMMARY:How to quantify energy landscapes of solids - Gareth Griffiths (TC
 M)
DTSTART:20090529T150000Z
DTEND:20090529T153000Z
UID:TALK16258@talks.cam.ac.uk
CONTACT:Daniel Cole
DESCRIPTION:"Artem R. Oganov and Mario Valle\, J. Chem. Phys. 130\, 104504
  (2009)":http://link.aip.org/link/?JCPSA6/130/104504/1\n\nWe explore wheth
 er the topology of energy landscapes in chemical systems obeys any rules a
 nd what these rules are. To answer this and related questions we use sever
 al tools: (i) Reduced energy surface and its density of states\, (ii) desc
 riptor of structure called fingerprint\nfunction\, which can be represente
 d as a one-dimensional function or a vector in abstract multidimensional s
 pace\, (iii) definition of a “distance” between two structures enablin
 g quantification of energy landscapes\, (iv) definition of a degree of ord
 er of a structure\, and (v) definitions of the quasi-entropy quantifying s
 tructural diversity. Our approach can be used for rationalizing large data
 bases of crystal structures and for tuning computational algorithms for st
 ructure prediction. It enables quantitative and intuitive representations 
 of\nenergy landscapes and reappraisal of some of the traditional chemical 
 notions and rules. Our analysis confirms the expectations that low-energy 
 minima are clustered in compact regions of configuration space\n(“funnel
 s”) and that chemical systems tend to have very few funnels\, sometimes 
 only one. This analysis can be applied to the physical properties of solid
 s\, opening new ways of discovering structure-property relations. We quant
 itatively demonstrate that crystals tend to adopt one of the few simplest 
 structures consistent with their\nchemistry\, providing a thermodynamic ju
 stification of Pauling's fifth rule.
LOCATION:TCM Seminar Room\, Cavendish Laboratory
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