STUDIES OF EXCESS ELECTRONS IN SODIUM-CHLORIDE CLUSTERS AND OF EXCESS PROTONS IN

2020-03-26 15:35:41

Na electronic clusters equal

责任者: BARNETT, RN;CHENG, HP;HAKKINEN, H;LANDMAN, U 单位: GEORGIA INST TECHNOL,SCH PHYS,ATLANTA,GA 30332.;UNIV JYVASKYLA,DEPT PHYS,SF-40351 JYVASKYLA,FINLAND. 来源出处: JOURNAL OF PHYSICAL CHEMISTRY, v 99, MAY 11 1995, p 7731- 7753 摘要: Electronic structure calculations using the local density functional method with nonlocal norm-conserving pseudopotentials, ab-initio molecular dynamics simulations, and a novel method of all-quantum simulations, combining a quantum path-integral description of the nuclear degrees of freedom with concurrent electronic structure calculations of the Born-Oppenheimer potential energy surface, were employed in investigations of the structure and dynamics of sodium chloride and protonated water clusters. For the sodium chloride clusters stoichiometric (NaCl)(n), 1 less than or equal to n less than or equal to 4, and nonstoichiometric metallization sequences Na4Clm, 0 less than or equal to m less than or equal to 3, Na3Clm, 0 less than or equal to m less than or equal to 2, Na2Clm, m = 1 and 2, and Na14Cl14-n, 1 less than or equal to n less than or equal to 6 and n = 10, were investigated. Analysis of various electronic properties (Kohn-Sham one-electron eigenvalue spectra, ionization potentials, participation ratios of Kohn-Sham orbitals), as well as multiple F-center formation energies, suggests that Na14Cl14-n clusters, starting from the cuboid Na14Cl13 nanocrystal, can be characterized as Na-n(NaCl)(14-n) having a phase-separated metallic part Na-n. The Na14Cl9 (or Na14Cl9+) cluster exhibits a face (surface) segregated metallic Na-5 (Na-5(+)) over-layer, the stability of which is demonstrated by a molecular dynamics simulation at 660 K. In analogy with color centers in bulk ionic crystals, the excess electrons in the halogen-deficient clusters in the various metallization sequences occupy energy levels which are split from the bottom of the unoccupied conduction band of the corresponding stoichiometric parent. Analysis of the electronic spatial distributions and participation ratios indicates that the excess electrons are of a more delocalized nature in comparison with the electrons occupying the p-like valence band. Using electronic structure, structural optimization, and all-quantum simulations, structures and energetics of H3O+, (H2OH+, (H2O)(n)M(+), n = 1 and 2 for M = Li, Na, and NH4+, (NH3H+, and the mixed (NH3)(H2OH+ cluster are described and analyzed. The quantum nature of the hydrogens in the protonated water clusters, as well as tunneling enhancement of the inversion isomerization in H3O+ at 150 K, is demonstrated and discussed. 关键词: PLASMID DNA; STRAND BREAK; AQUEOUS SOLUTION; TEMPERATURE; LIFETIME OF HYDROXYL RADICAL HYDROXYL RADICAL; ALKALI-HALIDE CLUSTERS; DENSITY-FUNCTIONAL THEORY; PLANE-WAVE CALCULATIONS; GAS-PHASE SOLVATION; MOLECULAR-DYNAMICS; QUANTUM CALCULATIONS; GAS-PHASE SOLVATION; MOLECULAR-DYNAMICS; QUANTUM SIMULATION; METAL-CLUSTERS; EFFICIENT PSEUDOPOTENTIALS; LARGE MATRICES; SIMULATION; METAL-CLUSTERS; EFFICIENT PSEUDOPOTENTIALS; LARGE MATRICES; BAND-STRUCTURE BAND-STRUCTURE