Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Electron-hole correlations in semiconductor quantum dots with
  tight-binding wave functions   The electron-hole states of semiconductor quantum dots are investigated
within the framework of empirical tight-binding descriptions for Si, as an
example of an indirect gap material, and InAs and CdSe as examples of typical
III-V and II-VI direct-gap materials. The electron-hole Coulomb interaction is
largely insensitive to both the real-space description of the atomic basis
orbitals and different ways of optimizing the tight-binding parameters.
Tight-binding parameters that are optimized to give the best effective masses
significantly improve the energies of the excitonic states due to the better
single-particle energies. However, the Coulomb interaction does not vary much
between different parameterizations. In addition, the sensitivity of the
Coulomb interaction to the choice of atomic or bitals decreases with increasing
dot size. Quantitatively, tight-binding treatments of correlation effects are
reliable for dots with radii larger than 15--20 angstrom. The calculated
excitonic gaps are in good agreement with recent photoluminescence data for Si
and CdSe but agree less well for InAs. Further, the effective range of the
electron-hole exchange interaction is investigated in detail. In quantum dots
of the direct-gap materials InAs and CdSe, the exchange interaction can be
long-ranged, extending over the whole dot when there is no local (onsite)
orthogonality between the electron and hole wave functions. By contrast, for Si
quantum dots the extra phase factor due to the indirect gap effectively limits
the range to about 15 angstrom, independent of the dot size.

32
The categories of this paper are: atom-ph
24
The categories of this paper are: dg-ga
12
The categories of this paper are: nucl-th
37
The categories of this paper are: supr-con
9
The categories of this paper are: nlin
5
The categories of this paper are: gr-qc
11
The categories of this paper are: hep-lat
26
The categories of this paper are: bayes-an
0
The categories of this paper are: hep-ph
28
The categories of this paper are: alg-geom
31
The categories of this paper are: ao-sci
2
The categories of this paper are: math
23
The categories of this paper are: solv-int
29
The categories of this paper are: funct-an
22
The categories of this paper are: chao-dyn
6
The categories of this paper are: astro-ph