As a rather different application, we consider the usefulness of the STM approach for VtC transitions in xray emission spectroscopy (VtC-XES), which is beginning to attract attention within the quantum chemistry community. This represents a first step in extending Slater-type approaches to core-excited rather than core-ionized states. Within the context of DFT, VtC-XES is typically simulated by applying linear-response time-dependent DFT to a reference determinant that contains a core hole, 114,120 as a ∆SCF approach would require state-by-state constrained SCF calculations to place an electron in each of the valence virtual orbitals. In contrast, using STM with just two SCF calculations one can obtain the entire spectrum, using the formula Both eigenvalues are computed from a single fractionalelectron calculation with n i = 1/2 in the core 1s orbital.