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SUMMARY:Space projected electrical conductivity and spectral properties of
  the conduction matrix - Dave Drabold (Ohio University)
DTSTART:20210310T160000Z
DTEND:20210310T170000Z
UID:TALK156013@talks.cam.ac.uk
CONTACT:Chuck Witt
DESCRIPTION:In this talk\, the Kubo–Greenwood formula is utilized to pro
 ject the electronic conductivity into real space\, and a Hermitian positiv
 e semidefinite matrix Γ is discussed\, which is called the conduction mat
 rix\, that reduces the computation of spatial conduction activity to a dia
 gonalization. It is shown that for low‐density amorphous carbon\, connec
 ted sp2rings and sp chains are conduction‐active sites in the network. I
 n amorphous silicon\, transport involves hopping through tail states media
 ted by the defects near the Fermi level. It is found that for liquid silic
 on\, thermal fluctuations induce spatial and temporal conductivity fluctua
 tions in the material. The frequency‐dependent absorption of light as a 
 function of wavelength in an amorphous silicon suboxide (a‐SiO1.3) is al
 so studied. It is shown that the absorption is strongly frequency dependen
 t and selects out different oxygen vacancy subnetworks depending on the fr
 equency. Γ is diagonalized to obtain conduction eigenvalues and eigenvect
 ors\, and it is shown that the density of states of the eigenvalues for FC
 C aluminum has an extended spectral tail that distinguishes metals from in
 sulators and semiconductors. We finally apply the method to study an insul
 ator-metal transition in a silver-doped chalcogenide glass.  The method is
  easy to implement with any electronic structure code\, providing suitable
  estimates for single‐particle electronic states and energies.
LOCATION:Zoom
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