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CATEGORIES:Theory of Condensed Matter
SUMMARY:Introducing Topological Quantum Chemistry and Topo
logical Materials Data Base - Dr Maia Vergniory\,
Donostia International Physics Center
DTSTART;TZID=Europe/London:20191031T141500
DTEND;TZID=Europe/London:20191031T151500
UID:TALK127543AThttp://talks.cam.ac.uk
URL:http://talks.cam.ac.uk/talk/index/127543
DESCRIPTION:In this talk a new field that classifies all topol
ogical crystalline phases of all known materials w
ill be introduced: Topological Quantum Chemistry (
TQC). It links the chemical and symmetry structure
of a given material with its topological properti
es. This field tabulates the data of the 10398 rea
l-space atomic limits of materials\, and solves th
e compatibility relations of electronic bands in m
omentum space. A material that is not an atomic li
mit or whose bands do not satisfy the compatibilit
y relations\, is a topological insulator/ semimeta
l. We use TQC to find the topological stoichiometr
ic non-magnetic\, ``high-quality'' materials in th
e world. We develop several codes which can comput
e all characters of all symmetries at all high-sym
metry points in the Brillouin Zone (BZ). Using TQC
we then develop codes to check which materials ar
e topological. Out of 26938 stoichiometric materia
ls in our filtered ICSD database\, we find around
7300 topological materials. For the majority of th
e "high-quality" topological materials\, we comput
e: the topological class\, the symmetry(ies) that
protects the topological class\, the representatio
ns at high symmetry points and the direct gap (for
insulators)\, and the topological index. For topo
logical semimetals we then compute whether the sys
tem becomes a topological insulator (whose index/c
lass we compute) upon breaking symmetries - useful
for experiments. Our exhaustive results show that
a large proportion of all materials in nature are
topological. I will also explain an open-source c
ode and end-user button on the Bilbao Crystallogra
phic Server (http://www.cryst.ehu.es/cgi-bin/cryst
/programs/topological.pl) which checks the topolog
y of any material and a new materials data base (h
ttps://www.topologicalquantumchemistry.com/).
LOCATION:TCM Seminar Room\, Cavendish Laboratory
CONTACT:Bartomeu Monserrat
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