  An experimental group at Beijing[Yueyang Zhai, ${\it et. al.}$, Phys. Rev. A
${\bf 87}$, 063638 (2013)] introduced the method of standing-wave pulse
sequence for efficiently preparing ultracold bosonic atoms into a specific
excited band in a 1-dimensional optical lattice. Here, we report a theoretical
extension of their work to the problem of 1-dimensional bichromatic
superlattice. We find that varying the lattice parameters leads to the
so-called Dirac point where a pair of excited bands crosses. This paper thus
discusses ${\it simultaneously}$ the efficient excitation of the wave packet to
the proximity of the Dirac point and its subsequent dynamics in the force field
of a parabolic trap. With the aid of a toy model, we theoretically unravel the
mechanism of the efficient preparation, and then numerically explore optimal
pulse-sequence parameters for a realistic situation. We find an optimized
sequence of a bichromatic optical lattice that excites more than 99% of the
atoms to the 1st and 2nd excited bands within 100 $\mu$s without the harmonic
trap. Our main finding is that the system permitting the Dirac point possesses
a region of parameters where the excited energy bands become nearly parabolic,
conducive to robust coherence and isochronicity. We also provide an appropriate
data set for future experimentation, including effects of the atom-atom
interaction by way of the mean-field nonlinear term.
