科研之友
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摘要
We present both theoretical ab-initio results within the Hedin%26apos;s GW approximation and experimental angle-resolved photoemission and scanning tunneling spectroscopymeasurements on TiSe2. With respect to the density-functional Kohn-Sham metallic picture, the many-body GW self-energy leads to a approximate to 0.2- eV band-gap insulator consistent with our STS spectra at 5 K. The highest valence and the lowest conduction bands are strongly renormalized, with a loss of k(2) parabolic dispersion toward a k(4) shape. In particular, GW moves the top of valence moved toward a circle of points away from Gamma, arising in a Mexican hat shape commonly associated with an excitonic insulator. Our calculations are in good agreement with experiment.
- 出版日期2012-5-8
