A method is described for using resonant x-ray scattering to separately quantify the charge (valence) modulation and the strain wave associated with a charge density wave. The essence of the method is a separation of the atomic form factor into a “raw” amplitude $f_R\left(\omega \right)$ and a valence-dependent amplitude $f_D\left(\omega \right)$ which in many cases may be determined independently from absorption measurements. The advantage of this separation is that the strain wave follows the average quantity ${\mid f_R\left(\omega \right)+⟨v⟩f_D\left(\omega \right)\mid }^2$, whereas the charge modulation follows only ${\mid f_D\left(\omega \right)\mid }^2$. This allows the two distinct modulations to be quantified separately. A scheme for characterizing a given CDW as Peierls-like or Wigner-like follows naturally. The method is illustrated for an idealized model of a one-dimensional chain.

• Received 16 August 2006

DOI:https://doi.org/10.1103/PhysRevB.74.195113