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First-Principles Computation Platform (Theoretical prediction of topological and related quantum materials)

 
  First-Principles simulations of electronic structure and spectral function are perfomed under the framework of density functional theory (DFT). The main programs employed in our calculations are VASP and ABINIT. The Feynman cluster at Princeton University provides computation power and various resources. We also collaborate with other institutions (including NUS and NEU) for complementary resources.

 
 
Some examples of our theoretical predictions

Weyl semimetals: Massless Yet Real (2015);

PhysicsWorld (March, 2016)

PhysicsWorld News (July, 2015)

Topo.Insulators: Nature Physics News Link (2009)

Nexus Fermions in spin-orbit materials (2017) (also see below)


Pedagogical Lectures

(Prediction of) Half-Heusler ternary compounds as new multifunctional experimental platforms for topological quantum phenomena.
Published in H. Lin, L. A. Wray, Y. Xia, et al., Nature Materials 9, 546 (2010).


(Prediction of) Nexus fermions in topological symmorphic crystalline metals Published in Guoqing Chang, Su-Yang Xu et al., Scientific Reports 7, 1688 (2017).

Some recent theoretical predictions: S.-M. Huang, S.-Y. Xu, I. Belopolski, et al., Nature Commun. 6:7373 (2015).

(Prediction of) Drumhead Surface States and Topological Nodal-Line Fermions in TlTaSe2.
G. Bian.,T.-R. Chang., H. Zheng, et al., arXiv:1508.07521 (2015).

(Prediction of) Magnetic and noncentrosymmetric Weyl fermion semimetals in the RAlX family of compounds (R=rare earth, Al=aluminium, X=Si, Ge).
G. Chang, B. Singh, S.-Y. Xu, et al., arXiv:1604.02124

(Prediction of) A strongly robust Weyl fermion semimetal state in Ta3S2.
G. Chang, S.-Y. Xu, D. S. Sanchez, et al., Science Advances (2015).

Prediction of an arc-tunable Weyl Fermion metallic state in MoxW1-xTe2
T.-R. Chang, S.-Y. Xu, G. Chang et al. Nature Commun. 7:10639 (2016)

(Prediction of) A new type of Weyl semimetal with quadratic double Weyl fermions in SrSi2
S.-M. Huang, S.-Y. Xu, I. Belopolski et al., PNAS 113, 1180 (2015)

(Prediction & Experiment together) Topological Nodal-Line Fermions in Spin-Orbit Metal PbTaSe2

G. Bian, T.-R. Chang, R. Sankar, et al. Nature Commun. 7:10556 (2016, submitted Nov 2015)

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Bi2Se3 class of Topo.Insulator Materials : Nature Physics News Link (2009)


 
 
  MoS21  
 
Observation of monolayer valence band spin-orbit effect and induced quantum well states in MoX2
Published in Nasser Alidoust, Guang Bian, Su-Yang Xu, et al.,
Nature Commun. 5, 4673 (2014)

 
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A Weyl Fermion semimetal with surface Fermi arcs in the transition metal monopnictide TaAs class.
Published in S.-M. Huang, S.-Y. Xu, I. Belopolski, et al., Nature Commun. 6:7373 (2015).

 
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Drumhead Surface States and Topological Nodal-Line Fermions in TlTaSe2.
G. Bian.,T.-R. Chang., H. Zheng, et al., arXiv:1508.07521 (2015).

 
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Magnetic and noncentrosymmetric Weyl fermion semimetals in the RAlX family of compounds (R=rare earth, Al=aluminium, X=Si, Ge).
G. Chang, B. Singh, S.-Y. Xu, et al., arXiv:1604.02124

 
 

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See theoretical calculations in "Signatures of the Adler-Bell-Jackiw chiral anomaly in a Weyl semimetal".
Nature Communications 7:10735 (2016)

 
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Room-temperature magnetic topological semimetal state in half-metallic Heusler Co2TiX (X=Si, Ge, or Sn).
G. Chang, S.-Y. Xu, H. Zheng, et al., arXiv:1603.01255

 
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A strongly robust Weyl fermion semimetal state in TaS.
G. Chang, S.-Y. Xu, D. S. Sanchez, et al., arXiv:1512.08781 (2015).

 
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Criteria for Directly Detecting Topological Fermi Arcs in Weyl Semimetals
I. Belopolski, S.-Y. Xu, D. S. Sanchez et al. Phys. Rev. Lett. 116, 066802 (2016)

 
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Prediction of an arc-tunable Weyl Fermion metallic state in MoxW1-xTe2
T.-R. Chang, S.-Y. Xu, G. Chang et al. Nature Commun. 7:10639 (2016)

 
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A new type of Weyl semimetal with quadratic double Weyl fermions in SrSi2
S.-M. Huang, S.-Y. Xu, I. Belopolski et al., PNAS 113, 1180 (2015)

 
  NbSe2  
Half-Heusler ternary compounds as new multifunctional experimental platforms for topological quantum phenomena.
Published in H. Lin, L. A. Wray, Y. Xia, et al., Nature Materials 9, 546 (2010).

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  Topological Nodal-Line Fermions in Spin-Orbit Metal PbTaSe2
G. Bian, T.-R. Chang, R. Sankar, et al. Nature Commun. 7:10556 (2016, submitted Nov 2015)

 
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Signatures of Fermi Arcs in the Quasiparticle Interferences of the Weyl Semimetals TaAs and NbP
G. Chang, S.-Y. Xu, H. Zheng et al., Phys. Rev. Lett. 116, 066601 (2016)


 
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Bi2Se3 class of Topo.Insulator Materials : Nature Physics News Link (2009)