  The electronic band structures of Bi${}_{1-x}$Sb${}_{x}$ thin films can be
varied as a function of temperature, pressure, stoichiometry, film thickness
and growth orientation. We here show how different anisotropic
single-Dirac-cones can be constructed in a Bi${}_{1-x}$Sb${}_{x}$ thin film for
different applications or research purposes. For predicting anisotropic
single-Dirac-cones, we have developed an iterative-two-dimensional-two-band
model to get a consistent inverse-effective-mass-tensor and band-gap, which can
be used in a general two-dimensional system that has a non-parabolic dispersion
relation as in a Bi${}_{1-x}$Sb${}_{x}$ thin film system.
