Fig. 1. Principal component analysis of the linearized structural sensitivity of the calculated XES spectrum of Fe(CO)5. (a) Singular values sk (red) and sum of the singular values (blue) in descending order. (b) Visualization of the sensitivity modes qk corresponding to the four largest singular values. (c) Calculated XES spectrum (upper panel) and principal component structural sensitivities δσPCk (lower panel). The color-coded shaded areas indicate the linearized change in the calculated spectrum for distortions of Qk = ±4 pm.
