As shown in Equation (12.2), the accuracy of simultaneously and independently obtaining fractions of the transient species and their corresponding transient spectra can be challenging. Current approaches using MIA and MXAN have accomplished the first steps. The requirement is to combine these approaches with accurate potential energy surfaces around metal centers, which by itself is already difficult. Since MXAN and MIA or similar approaches take advantage of the structurally sensitive multiple scattering features in a relatively narrow energy window and with varying combined nuclear coordinates, they succeeded in extracting multiple species and their fractions simultaneously. However, the current development has not been incorporated in high level calculations for both electronic and nuclear structural contributions. This remains a challenge for extracting accurate structures when the two effects interfere.