Ground and Electronically Excited States of Main-Group-Metal-Doped B 20 Double Rings.

Ab initio coupled-cluster, electron propagator, and Møller-Plesset second-order perturbation theory calculations are utilized to analyze the low-lying electronic states of several metal-doped B 20 . In the ground state, the presently focused AB 20 /EB 20 (A = Li, Na, and K; E = Mg and Ca) consist of charge-separated A + B 20 - /E 2+ B 20 2- frameworks. The excited electronic states of AB 20 and EB 20 + were analyzed by computing the vertical electron attachment energies (VEAEs) of AB 20 + and EB 20 2+ . In several excited states, the radical electron is predominantly localized on the B 20 frames, which are counterparts of the low-lying states of bare B 20 - . A variety of basis sets were tested on obtaining VEAEs, and the aug-cc-pVDZ/ A,E d-aug-cc-pVDZ/ B combination provided the best accuracy-efficiency compromise on them. Furthermore, this work analyzes the Rydberg-like excited states of AB 20 and EB 20 + and will serve as a guide for future studies on similar metal-doped boron systems.