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SUMMARY:Introducing Topological Quantum Chemistry and Topological Material
 s Data Base - Dr Maia Vergniory\, Donostia International Physics Center
DTSTART:20191031T141500Z
DTEND:20191031T151500Z
UID:TALK127543@talks.cam.ac.uk
CONTACT:Bartomeu Monserrat
DESCRIPTION:In this talk a new field that classifies all topological cryst
 alline phases of all known materials will be introduced: Topological Quant
 um Chemistry (TQC). It links the chemical and symmetry structure of a give
 n material with its topological properties. This field tabulates the data 
 of the 10398 real-space atomic limits of materials\, and solves the compat
 ibility relations of electronic bands in momentum space. A material that i
 s not an atomic limit or whose bands do not satisfy the compatibility rela
 tions\, is a topological insulator/ semimetal. We use TQC to find the topo
 logical stoichiometric non-magnetic\, ``high-quality'' materials in the wo
 rld. We develop several codes which can compute all characters of all symm
 etries at all high-symmetry points in the Brillouin Zone (BZ). Using TQC w
 e then develop codes to check which materials are topological. Out of 2693
 8 stoichiometric materials in our filtered ICSD database\, we find around 
 7300 topological materials. For the majority of the "high-quality" topolog
 ical materials\, we compute: the topological class\, the symmetry(ies) tha
 t protects the topological class\, the representations at high symmetry po
 ints and the direct gap (for insulators)\, and the topological index. For 
 topological semimetals we then compute whether the system becomes a topolo
 gical insulator (whose index/class we compute) upon breaking symmetries - 
 useful for experiments. Our exhaustive results show that a large proportio
 n of all materials in nature are topological. I will also explain an open-
 source code and end-user button on the Bilbao Crystallographic Server (htt
 p://www.cryst.ehu.es/cgi-bin/cryst/programs/topological.pl) which checks t
 he topology of any material and a new materials data base (https://www.top
 ologicalquantumchemistry.com/).
LOCATION:TCM Seminar Room\, Cavendish Laboratory
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