Experimental valence X-ray photoelectron (VXPS) and Auger electron spectra (AES) of (Li-F, S)-elements for solid substances [Li-compounds (Li-metal, Li₂O, LiF, LiCl), Be, B, graphite, GaN, SiO₂, and five polymers (PP, P4VP, PVME, PTFE, PPS)] were analyzed by density-functional theory (DFT) calculations using the model molecules of the unit cell. In the calculations, we use deMon DFT program to estimate VXPS, core-electron binding energies (CEBEs), and KVV [{1s (core hole), valence (relaxation electron), valence (Auger electron)} in Auger transition notation designated via the three energy levels] AES of the solid substances. For the AES simulations, we evaluate theoretical kinetic energies of the AES with our modified calculation method. The modified kinetic energies correspond to two final-state holes at the ground state and at the generalized Slater’s transition-state in DFT calculations. Experimental KVV AES of the (Li-O) atoms in the substances agree considerably well with simulation of AES obtained with the maximum kinetic energies of the atoms, while, the experimental F KVV AES of LiF is almost in accordance with the spectra given from the transition-state kinetic energy calculations.