Nonmetal-to-metal transitions are among the most fascinating phenomena in material science, associated with strong correlations, large fluctuations, and related features relevant to applications in electronics, spintronics, and optics. Dissolving alkali metals in liquid ammonia results in the formation of solvated electrons, which are localised in dilute solutions but exhibit metallic behaviour at higher concentrations, forming a disordered liquid metal. The electrolyte-to-metal transition in these systems appears to be gradual, but its microscopic origins remain poorly understood. Here, we provide a detailed time-resolved picture of the electrolyte-to-metal transition in solutions of lithium in liquid ammonia, employing ab initio molecular dynamics and many-body perturbation theory, which are validated against photoelectron spectroscopy experiments. We find a rapid flipping between metallic and electrolyte states that persist only on a sub-picosecond timescale within a broad range of concentrations. These flips, occurring within femtoseconds, are characterised by abrupt opening and closing of the band gap, which is connected with only minute changes in the solution structure and the associated electron density.

• Publikační typ
• časopisecké články MeSH

The ability of a ring-shaped molecule to sustain a global aromatic or antiaromatic ring current when placed in a magnetic field indicates that its electronic wave function is coherently delocalized around its whole circumference. Large molecules that display this behavior are attractive components for molecular electronic devices, but this phenomenon is rare in neutral molecules with circuits of more than 40 π-electrons. Here, we use theoretical methods to investigate how the global ring currents evolve with increasing ring size in cyclic molecular nanobelts built from edge-fused porphyrins. Our results indicate that a global ring current persists in neutral nanobelts with Hückel circuits of 220 π-electrons (22 porphyrin units, circumference 18.6 nm). Our predictions are validated by using coupled clusters to construct a density functional approximation (denoted as OX-B3LYP) that accurately describes these nanobelts and by checking compliance with Koopmans' theorem.

• Klíčová slova
• aromaticity, density functional theory, molecular electronics, porphyrin nanobelts, ring current,
• Publikační typ
• časopisecké články MeSH