Analysis of scanning tunneling microscopy images of the charge-density-wave phase in quasi-one-dimensional Rb_0.3MoO₃

The experimental scanning tunneling microscopy (STM) images for the charge-density-wave (CDW) phase of the blue bronze Rb_0.3MoO₃ have been successfully explained on the basis of first-principles density functional theory 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 wave vector of the modulation probed by STM are reported. The calculated changes in the surface nesting vector are consistent with the observed experimental inhomogeneities.