  The experimental STM images for the CDW phase of the blue bronze RbMoO3 have
been successfully explained on the basis of first-principles DFT calculations.
Although the density of states near the Fermi level strongly concentrates in
two of the three types of Mo atoms Mo-II and Mo-III, the STM measurement mostly
probes the contribution of the uppermost O atoms of the surface, associated
with the Mo-IO6 octahedra. In addition, it is found that the surface
concentration of Rb atoms plays a key role in determining the surface nesting
vector and hence the periodicity of the CDW modulation. Significant
experimental inhomogeneities of the b* surface component of the wavevector of
the modulation, probed by STM, are reported. The calculated changes in the
surface nesting vector are consistent with the observed experimental
inhomogeneities.
