Energetics and structures of neutral and charged Si{sub n} (n{le}10) and sodium-doped Si{sub n}Na clusters
- School of Physics, Georgia Institute of Technology, Atlanta, Georgia 30332-0430 (United States)
Energetics and structures of neutral and charged Si{sub n} (n{le}10) and sodium-doped Si{sub n}Na clusters have been investigated using local spin density functional electronic structure calculations and structural optimizations, with and without exchange-correlation gradient corrections. For the Si{sub n} clusters, the monomer separation energies show local maxima for n=4, 7, and 10. The vertical and adiabatic ionization potentials are smaller than the values for the Si atom and exhibit odd-even oscillations with values in agreement with experiments, and the adiabatic electron affinities show local minima for n=4, 7, and 10, with the value for the heptamer being the smallest, in agreement with the experimentally measured pattern. Binding of Na to Si{sub n} is characterized by charge transfer from the sodium resulting in the development of significant dipole moments for the Si{sub n}Na clusters. The binding energy of Na to Si{sub n} oscillates as a function of n, with local maxima for n=2, 5, and 9, and local minima for n=4, 7, and 10, with the value for n=7 being the smallest. A similar trend is found for the vertical and adiabatic ionization potentials of the doped clusters, correlating with the electron affinity trend exhibited by the Si{sub n} clusters, and in agreement with recent measurements. In the optimal adsorption geometry of H{sub 2}O on the Si{sub 7}Na cluster, the oxygen is bonded to the Na, with a hydration energy significantly higher than that of an isolated sodium atom. The vertical and adiabatic ionization potentials of NaH{sub 2}O are lower than those of Si{sub 7}NaH{sub 2}O, and the values for the latter are lower, by {approx}0.2 eV, than those of the unhydrated Si{sub 7}Na cluster. {copyright} {ital 1997} {ital The American Physical Society}
- OSTI ID:
- 530963
- Journal Information:
- Physical Review, B: Condensed Matter, Vol. 55, Issue 12; Other Information: PBD: Mar 1997
- Country of Publication:
- United States
- Language:
- English
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