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

Figure 7

Schematic diagrams of (a) |𝐶_𝛽𝜆(𝑞)|²𝐺⁽⁻⁾_𝜆𝛾1(𝜔₁)𝑃₊(𝜆,𝛾₁), (b) |𝐶_𝛽𝜆(𝑞)|²𝐺⁽⁺⁾_𝜆𝛾1(𝜔₁)𝑃₋(𝜆,𝛾₁), (c) |𝐶_𝜆𝛼(𝑞)|²𝐺⁽⁻⁾_𝛽𝜆(𝜔₁₂₃)[𝑃₊(𝛽,𝜆)−𝑃₊(𝛾₁,𝜆)], and (d) |𝐶_𝜆𝛼(𝑞)|²𝐺⁽⁺⁾_𝛽𝜆(𝜔₁₂₃)[𝑃₋(𝛽,𝜆)−𝑃₋(𝛾₁,𝜆)] in Γ⁽²¹⁾_{𝛽𝛾1𝛾2𝛼}(𝜔₁,𝜔₂,𝜔₃).

(a)

(b)

(c)

(d)