Hai-Shun Wu

First principles study of the structure, electronic state and stability of SinC−m anions

Abstract Structure, electronic state and energy of SinC− and SinC−2 (n=1–7) anions have been investigated using the density functional theory. Structural optimization and frequency analysis are performed at the level B3LYP/6-311G(d). The charged-induced structural changes in these anions have been discussed. The strong C–C bond is also favored over C–Si bonds in the SinC−m anions in comparison with corresponding neutral cluster. Among different SinC− and SinC−2 (n=1–7) anions, Si 3 C − , Si 5 C − and Si2C−2 are most stable. Their stability has a decreasing tendency with the increase in the size of these clusters.

Ab initio studies on the structures, adiabatic ionization potentials and stability of SiCm−1+ clusters

Abstract Structural and electronic properties of semiconductor binary SiC m −1 + ( m =3–16) clusters have been investigated using the B3LYP-DFT method. Full structural optimization and the adiabatic ionization potential calculation are performed with the basis of 6-311G ∗ . These results show that SiC m −1 + ( m =3–10) isomers have chained structures and SiC m −1 + ( m =11–16) species have ring structures. Si atom favor to bond at end in chained isomers whereas C atoms themselves favor to bond in the cyclic structures. The stability of the SiC m −1 + ( m =3–16) clusters with odd m are greater than that with even m . The relative stability becomes more and more weak.

Structure and stability of boron nitride cages

The structure and energy of boron nitrides (BN)n (n = 10−41), have been investigated theoretically. The most stable cages have been constructed on the basis of a simple design principle, and the predicated stability has been validated at the B3LYP/6-31G* level of theory. Among these, the Th, symmetrical (BN)12 cluster has been confirmed to be the most stable cage on the basis of the calculated disproportation energy and binding energy per BN unit.

Structure and magnetic properties of [FePt/Ag]10 multilayer films

Abstract[FePt/Ag]10 multilayers were deposited on glass substrates by magnetron sputtering. After being annealed at 550°C for 30 min, the coercivities of [FePt/Ag]10 multilayer films were observably improved. Magnetic properties of [FePt/Ag]10 multilayer films are influenced by the Ag content. The highest coercivity is obtained for those multilayer films that the Ag content is about 25%. The analysis for the remanence curves shows that the lower FePt layer thickness is favorable for decreasing the intergranular interaction. Result of XRD shows that a thick Ag layer can enhance the intensity of FePt(00l) peak. A magnetic activation volume of the order of 10−24 m3 is obtained by the measurement of magnetic viscosity, showing that it is promising to be ultrahigh density recording media.