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SUMMARY:CALYPSO: A Useful Tool for Discovering Novel Structures and Proper
 ties of Materials at Extreme Conditions - Yanming Ma\, Jilin University
DTSTART:20140905T143000Z
DTEND:20140905T153000Z
UID:TALK54140@talks.cam.ac.uk
CONTACT:Gareth Conduit
DESCRIPTION:Atomistic structures of materials occupy a central and often c
 ritical role\, when establishing a correspondence between materials perfor
 mance and their compositions. Therefore\, theoretical prediction of atomis
 tic structures of materials with the only given information of chemical co
 mpositions play a vital role in materials design\, but it is extremely dif
 ficult as it basically involves in classifying a huge number of energy min
 ima on the lattice energy surface. We have developed an efficient CALYPSO 
 approach [1-2] for structure prediction from "scratch" based on swarm opti
 mization algorithm by taking the advantage of swarm intelligence and the s
 pirit of structures smart learning. Symmetry constraints on structure gene
 rations\, bond characterization matrix for fingerprinting structures\, and
  geometric optimization are other irreplaceable ingredients of CALYPSO [1-
 2]. The method has been coded into CALYPSO software (http://www.calypso.cn
 ).\n\nIn this presentation\, I will give a short introduction into the pri
 nciple of CALYPSO structure prediction method [1-2]. Primary emphasis will
  be placed on its application into exploration of novel high-pressure stru
 ctures with exotic physics and chemistry not accessible to ambient pressur
 e. Examples will be presented towards to the prediction and its later expe
 rimental confirmation of insulating electride lithium [3]\, out-of-imagina
 tion cage structure of polymeric nitrogen [4]\, and unexpected chemical re
 actions of Fe and Xe\, and Ca and H2 at extreme conditions with the format
 ion of unusual stoichiometries. Reaction of Fe and Xe in the conditions of
  Earth core [5] might provide a possible solution of “missing Xe paradox
 ”. Reaction of Ca and H2 brings element one into sodalite cage [6].\n\n[
 1] Y. Wang\, J. Lv\, L.Zhu\, and Y. Ma\, Phys. Rev. B 82\, 094116 (2010).\
 n[2] Y. Wang\, J. Lv\, L.Zhu\, and Y. Ma\, Comput. Phys. Commun. 183\, 206
 3 (2012).\n[3] J. Lv\, Y. Wang\, L. Zhu\, and Y. Ma\, Phys. Rev. Lett. 106
 \, 015503 (2011).\n[4] X. Wang\, et al.\, Phys. Rev. Lett. 109\, 175502 (2
 012).\n[5] L. Zhu\, et al.\, Nature Chemistry\, doi:10.1038/nchem.1925 (20
 14).\n[6] H. Wang\, J. Tse\, K. Tanaka\, T. Iitaka\, and Y. Ma\, Proc. Nat
 l. Acad. Sci. USA\, 109\, 6463 (2012).\n
LOCATION:TCM Seminar Room\, Cavendish Laboratory
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