Wang Hong-Yan

Geometric, stable and electronic properties of Aun-2Y2 （n = 3 -8） clusters

Employing first-principles methods, based on the density function theory, and using the LANL2DZ basis sets, the ground-state geometric, the stable and the electronic properties of Aun–2Y2 clusters are investigated in this paper. Meanwhile, the differences in property among pure gold clusters, pure yttrium clusters, gold clusters doped with one yttrium atom, and gold clusters doped with two yttrium atoms are studied. We find that when gold clusters are doped by two yttrium atoms, the odd-even oscillatory behaviours of Aun–1Y and Aun disappear. The properties of Aun–2Y2 clusters are close to those of pure yttrium clusters.

Geometry and electronic properties of Cun (n≤9)

The equilibrium geometries and the atomization energies of Cun(n≤9) clusters have been calculated using the B3LYP/LANL2DZ method. It is shown that the clusters do not copy the bulk structures and undergo significant geometrical changes with size and the atomization energy per atom increases monotonically with size. By analysing the energy level distribution, the Fermi level, HOMO–LUMO gaps, the electron affinities and the ionization potentials are calculated and the results are in reasonable agreement with experiment. These electronic properties are found to be strongly structure dependent, which can be used to determine which of the low-lying structures is observed experimentally.

Double-Proton-Transfer Reaction in Guanine-Cytosine Base Pair Embedded in B-Form DNA

The double-proton-transfer reaction of the isolated guanine-cytosine (GC) base pair and four DNA trimers with different nucleobase sequences (dATGCAT, dGCGCGC, dTAGCTA, and dCGGCCG) are studied by quantum mechanical calculations using ONIOM(M06-2X/6-31G*:PM3). Proton-transfer patterns, energy and structural properties are analyzed to gain insight into the double-proton-transfer mechanism with consideration to environmental factors. In the gas phase, a stepwise mechanism is found for the dCGGCCG trimer, and a concerted mechanism is found in the other four models. The computational results demonstrate that electrostatic interaction of the peripheral and middle base pairs have a pronounced effect on double-proton-transfer pattern of GC base pairs. The structures with dATGCAT and dGCGCGC sequences facilitate H4a proton transfer and those with dTAGCTA and dCGGCCG sequence facilitate H1 proton transfer. The high proton affinity of cytosine at N3 facilitates H1 proton transfer. In aqueous solution, electrostatic interactions are reduced and the products of single-proton-transfer in the stepwise mechanism are stabilized. This results in a stepwise transfer pattern becoming favorable. Solvent effects favor the single-proton-transfer reaction more than gas phase conditions, but increase the reaction energy of double-proton-transfer. 1233 Acta Phys. ⁃Chim. Sin. 2013 Vol.29