Introducing Novel Materials with Diffuse Electrons for Applications in Redox Catalysis and Quantum Computing via Theoretical Calculations

Abstract

Diamond-like structures, where carbon atoms have been replaced with Li+ and C–C bonds with diamines, have currently been introduced as new materials, which can host diffuse electrons in the periphery of each lithium tetra-amine center. These materials display a diverse range of properties behaving as metals or semiconductors depending on the diamine chain length. Multi-reference wavefunction and density functional theory calculations were employed to study the electronic structure of these materials. Initially, gas phase calculations are performed on isolated (NH3)3LiNH2(CH2)1–10H2NLi(NH3)3 molecular strings. One diffuse electron surrounds the periphery of each −NH2Li(NH3)3 terminus. The two terminal electrons couple into a triplet and open-shell singlet states, which are nearly degenerate for long chains and as closed shell singlets for short. At intermediate lengths, the wavefunction of the ground-state singlet state mixes both open- and closed-shell configurations raising doubts about which configuration should be considered for density functional theory calculations. Observations from gas phase calculations accurately predict properties from the condense phase density functional theory calculations carried out for proposed crystalline Li-diamine materials, offering an avenue for further development and insight. Spin-polarized and unpolarized calculations are performed for the whole range of hydrocarbon sizes reporting geometrical and electronic band structures, spin density contours, and density of states. Diffuse electrons can be used for redox reactions or can serve as qubits for quantum computing. Future work will focus on decorating the hydrocarbon backbone with functional groups and/or bulky units, in order to facilitate or block the association between neighboring electrons for more controlled quantum computing applications and propose materials for selective redox catalysis.