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

Figure 8

Schematic diagrams of (a) |𝐶_𝛽𝜆(𝑞)|²𝐺⁽⁻⁾_𝜆𝛾1(𝜔₁₂)[𝑃₊(𝜆,𝛾₂)−𝑃₊(𝜆,𝛾₁)], (b) |𝐶_𝛽𝜆(𝑞)|²𝐺⁽⁺⁾_𝜆𝛾2(𝜔₁₂)[𝑃₋(𝜆,𝛾₂)−𝑃₋(𝜆,𝛾₁)], (c) |𝐶_𝜆𝛼(𝑞)|²𝐺⁽⁻⁾_𝛽𝜆(𝜔₁₂₃) [𝑃₊(𝛾₁,𝜆)−𝑃₊(𝛾₂,𝜆)], and (d) |𝐶_𝜆𝛼(𝑞)|²𝐺⁽⁺⁾_𝛽𝜆(𝜔₁₂₃) [𝑃₋(𝛾₁,𝜆)−𝑃₋(𝛾₂,𝜆)] in Γ⁽²²⁾_{𝛽𝛾1𝛾2𝛼}(𝜔₁,𝜔₂,𝜔₃).

(a)

(b)

(c)

(d)