Projection-Reduction Approach to Optical Conductivities for an Electron-Phonon System and Their Diagram Representation

Figure 4

Schematic diagrams of (a) |𝐶_𝛽𝜆(𝑞)|²𝐺⁽⁻⁾_𝜆𝛾(𝜔₁)𝑃₊(𝜆,𝛾), (b) |𝐶_𝛽𝜆(𝑞)|²𝐺⁽⁺⁾_𝜆𝛾(𝜔₁)𝑃₋(𝜆,𝛾), (c) |𝐶_𝜆𝛼(𝑞)|²𝐺⁽⁻⁾_𝛽𝜆(𝜔₁₂)[𝑃₊(𝛽,𝜆)−𝑃₊(𝛾,𝜆)], and (d) |𝐶_𝜆𝛼(𝑞)|²𝐺⁽⁺⁾_𝛽𝜆(𝜔₁₂)[𝑃₋(𝛽,𝜆)−𝑃₋(𝛾,𝜆)] in Γ⁽¹¹⁾_𝛽𝛾𝛼(𝜔₁,𝜔₂).

(a)

(b)

(c)

(d)