Metal Dependence of Signal Transmission through Molecular Quantum-Dot Cellular Automata (QCA): A Theoretical Study on Fe Ru and Os Mixed-Valence Complexes

摘要

Dynamic behavior of signal transmission through metal complexes [L5M-BL-ML5]⁵⁺ (M=Fe, Ru, Os, BL=pyrazine (>py), 4,4’-bipyridine (>bpy), L=NH3), which are simplified models of the molecular quantum-dot cellular automata (molecular QCA), is discussed from the viewpoint of one-electron theory, density functional theory. It is found that for >py complexes, the signal transmission time (tst) is Fe(0.6 fs) < Os(0.7 fs) < Ru(1.1 fs) and the signal amplitude (A) is Fe(0.05 e) < Os(0.06 e) < Ru(0.10 e). For >bpy complexes, tst and A are Fe(1.4 fs) < Os(1.7 fs) < Ru(2.5 fs) and Os(0.11 e) < Ru(0.12 e) < Fe(0.13 e), respectively. >Bpy complexes generally have stronger signal amplitude, but waste longer time for signal transmission than >py complexes. Among all complexes, Fe complex with >bpy BL shows the best result. These results are discussed from overlap integral and energy gap of molecular orbitals.