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The bonding and electronic properties of In

The structural evolution, electronic and magnetic properties of molybdenum and tungsten doped silicon clusters, TMSin− (TM = Mo, W; n = 8-17), have been investigated at density functional theory (DFT) level. The global minimum structure of each cluster has been searched globally based on a homemade genetic algorithm coupled with DFT calculations. The ground-state structure of each cluster has been confirmed by comparing the calculated photoelectron spectrum (PES) with the experimental one. Most sizes of MoSin− and WSin− clusters share the same geometric structures, and very similar electronic and magnetic properties. Small sized (n ≤ 13) clusters always adopt a pentagonal bipyramid TM@Si6 as the structural motif, while the larger sizes prefer a fullerene-type TM@Si14 structure. Compared to CrSin− clusters, the replacement of Cr atom by Mo and W atoms can increase the binding energy by about 0.2 eV and 0.3 eV, respectively. It also reveals that the total magnetic moments of these TMSin− (TM = Mo, W) clusters are all 1 μB, and have similar sources, but with different contributions from that of CrSin− clusters in most sizes.

A cryogenic beam apparatus for studying neutral clusters has been built and tested. The lowest beam temperature reaches less than 9 K at a repetition rate of 20 Hz. Mechanical decoupling from the refrigerator avoids misalignment during temperature ramping. Adopting a permanent magnet based magnetic deflector eliminates the hysteresis and electric noise of the traditional electromagnet and offers excellent reproducibility of the applied magnetic field. The mass spectrometer can operate in either Mass Spectroscopy Time-Of-Flight mode or Position-Sensitive Time-Of-Flight mode with spatial resolution better than 7 μm. Its performance is demonstrated with niobium and cobalt clusters.

Stretchable flexible conductive composites have received considerable attention recently. In this study, highly conductive and stretchable composites were synthesized using Ag microflakes (AgMFs), ...

Static dipole polarizabilities for the first 20 atoms and ions of the Periodic Table are calculated within a single theoretical scheme: the coupled-cluster method with a Hartree–Fock reference wavefunction using an augmented-polarization-consistent and polarization-consistent basis set. The values of the atomic polarizabilities of neutral atoms obtained here agree extremely well with the experimentally measured values. For the ions, all the calculations are consistent with experimental values with the highest resolution so far, except for the monovalent calcium ion, probably due to strong relativistic effects. To the best of our knowledge, this is the first time, applying a single theoretical scheme successfully predicts static polarizabilities of all 20 consecutive elements across 8 columns and more than 3 full periods being consistent with the experimentally measured values both for neutrals and ions. The results clearly signal the universality of this theoretical scheme for the atomic polarizability calculation, and should be easy to extend to other elements with weak relativistic effects. We adopt the CCSD(T) method with an augmented polarization-consistent and polarization-consistent basis set to calculate the atomic and ionic polarizabilities for the first 20 atoms and ions of the Periodic Table. Our calculation results are in good agreement with the experimental data with the highest accuracy so far and the reported high accuracy calculation results. Semi-logarithm plot of calculated static polarizabilities of neutral atoms (filled circles, black line) and ions (open circles). The colored lines join isoelectronic species.

Titanium-doped silicon clusters anions, TimSi − (m = 1‒2, n = 14‒20), have been investigated by photoelectron spectroscopy and density functional theory (DFT) calculations. Low-energy structures of TimSi − clusters have been globally searched using a genetic algorithm combined with DFT calculations. The electronic density of states and vertical detachment energies have been computed at the HSE06/aug-cc-pVDZ level and compared to the experimental data. Excellent agreement is found between theory and experiment especially in case of the singly doped clusters. In general, clusters with size m + n ≤ 17 prefer cage structures, while larger sized clusters evolve on a quasi-fullerene Ti@Si14 structural motif. Natural population analysis reveals that the Ti atoms possess negative charges and thus act as electron acceptors. The calculated binding energies and HOMO–LUMO gaps show that the clusters with cage structures have significantly higher stability, particularly Ti1Si16− and Ti2Si15−. One reason is that neutral Ti2Si15 exhibits a closed-shell electronic structure as a superatom, like Ti1Si16.

Size-selected anionic silicon clusters, Sin- (n=14-20), have been investigated by photoelectron spectroscopy and density functional theory (DFT) calculations. Low-energy structures of the clusters are globally searched for by using a genetic algorithm based on DFT calculations. The electronic density of states and VDEs have been simulated by using ten DFT functionals and compared to the experimental results. We systematically evaluated the DFT functionals for the calculation of the energetics of silicon clusters. CCSD(T) single-point energies based on MP2 optimized geometries for selected isomers of Sin- are also used as benchmark for the energy sequence. The HSE06 functional with aug-cc-pVDZ basis set is found to show the best performance. Our global minimum search corroborates that most of the lowest-energy structures of Sin- (n=14-20) clusters can be derived from assembling tricapped trigonal prisms (TTP) in various ways. For most sizes previous structures are confirmed, whereas for Si20- a new structure has been found., Comment: 9 pages, 4 figures, 3 tables