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The equilibrium geometries, stabilities and electronic properties of Be n + 1 and Be n Li (n=2–12) clusters have been systematically investigated by using the density-functional approach at B3LYP/6-31G(d) level. The resulting geometries show that Li prefers to be on the periphery of Be clusters. We also report polarizabilities for both series of Be n + 1 and Be n Li clusters. Our calculations demonstrate that Li impurity increases the polarizabilities of Be n + 1 clusters.

The equilibrium geometries and electronic properties of Na m Si n ( m + n ⩽ 7 ) clusters have been studied by using density functional theory at the B3LYP/6-311+G(d) level. The ground state structures of Na m Si n clusters can be obtained by adding one Na atom to Na m - 1 Si n clusters, and the Na atom locates on the site which maximally tends to form Na Si bonds. The Si-rich clusters are more stable than Na-rich clusters with the same number of atoms. The Si Si bond is stronger than the Na Si bond, and the latter is stronger than the Na Na bond. The vertical ionization potentials of Na m Si n clusters obtained by B3LYP are in good agreement with the experimental values available. For such a certain cluster size ( m + n = 4 , 5 , 6 , 7 ) , the energy gaps of the most stable Na m Si n clusters show odd–even oscillation with changing m, the clusters with odd Na atoms exhibit stronger chemical reactivity than those with even Na atoms.

Determinations of the lowest energy structures and electronic properties of MgBen (n=2-12) clusters were carried out by using density-functional theory. It was found that MgBe3 and MgBe9 clusters with higher binding energy and larger HOMO-LUMO gap are more stable than the neighboring clusters. The electronic properties from van der Waals to covalent and bulk metallic behavior in MgBen (n=2-12) clusters are discussed with the evolution of the size, and the data indicates Magnesium-doped Beryllium clusters already early appear some metallic-like features than host Ben clusters. By analyzing electronic properties of MgBen (n=2-12) clusters, it can be concluded that Mg-doped reduces the stabilities of Be clusters.

Tight-binding model is developed to study the structural and electronic properties of silver clusters. The ground state structures of Ag clusters up to 21 atoms are optimized by molecular dynamics-based genetic algorithm. The results on small Agn clusters (n = 3-9) are comparable to ab initio calculations. The size dependence of electronic properties such as density of states, s-d band separation, HOMO-LUMO gap, and ionization potentials are discussed. Magic number behavior at Ag2, Ag8, Ag14, Ag18, Ag20 is obtained, in agreement with the prediction of electronic ellipsoid shell model. We suggest that both the electronic and geometrical effect play significant role in the coinage metal clusters.

Using an empirical many-body potential and Genetic Algorithm, the geometry of Rh n ( n=9, 13, 15, 17, 19 ) clusters has been optimized. Based on the optimization geometry, the ground-state magnetic properties and related electronic properties of rhodium clusters are calculated by using a spd-band model Hamiltonian in the unrestricted Hartree–Fock approximation. Results are given for the average magnetic moment per atom μ n , the spin-polarized charge distribution within the cluster, and the sp and the d electronic density of state. The calculated μ n are in good agreement with the experiments.

Using an empirical many-body potential and a genetic algorithm, the geometries of small V 3 to V 19 clusters have been optimized. We find that the clusters do not mimic the bulk structure and undergo significant geometrical changes with size. Based on the optimization geometries, the d electronic structure and magnetic properties of V clusters are studied, by using a Hubbard tight-binding model Hamiltonian in the unrestricted Hartree-Fock approximation. The calculated average magnetic moments for these clusters are consistent with the upper limits obtained from experiments. The total density of states (TDOS) and the local density of states (LDOS) of d electrons shed light on the evolution of the electronic properties.

A genetic algorithm has been employed, in combination with the first-principles Pacheco-Ramalho intermolecular potential, not only including its two-body part but also its dominant three-body term, to predict the magic number structure of neutral $({\mathrm{C}}_{60}{)}_{N}$ clusters up to $N=25.$ The calculated second finite difference of the total energy shows that the $({\mathrm{C}}_{60}{)}_{N}$ clusters with $N=7,$ 13, 18, and 22 are particularly stable. Present results indicate that the three-body effect is not significant for $({\mathrm{C}}_{60}{)}_{N}$ clusters with $Nl~17,$ but above $N=17$ we must consider the role played by the three-body dispersion term. It is found that $N=17$ is a crossover from icosahedral to decahedral, and for $Ng~23$ (inclusion of the three-body term) icosahedral structures are always lower in energy than decahedra.

An interacting Bose gas in a harmonic trap is investigated for its energy shift due to combined effect of the inter-particle interaction and the trap. Compared with the case in free space, it is seen that the interactions have opposite effects on the transition temperature of Bose–Einstein condensation.

Through first-principles calculations, we found doping carbon atoms onto BN monolayers (BNC) could significantly strengthen the Li bond on this material. Unlike the weak bond strength between Li atoms and the pristine BN layer, it is observed that Li atoms are strongly hybridized and donate their electrons to the doped substrate, which is responsible for the enhanced binding energy. Li adsorbed on the BNC layer can serve as a high-capacity hydrogen storage medium, without forming clusters, which can be recycled at room temperature. Eight polarized H(2) molecules are attached to two Li atoms with an optimal binding energy of 0.16-0.28 eV/H(2), which results from the electrostatic interaction of the polarized charge of hydrogen molecules with the electric field induced by positive Li atoms. This practical carbon-tuned BN-Li complex can work as a very high-capacity hydrogen storage medium with a gravimetric density of hydrogen of 12.2 wt%, which is much higher than the gravimetric goal of 5.5 wt % hydrogen set by the U.S. Department of Energy for 2015.

To improve the diagnosis and treatment of paratesticular embryonal rhabdomyosarcoma (PER).We retrospectively studied the clinical data of 5 cases of PER treated from 1997 to 2009 and reviewed the relevant literature, focusing on its clinical manifestations, diagnosis and treatment.The 5 cases of PER, 2 involving the spermatic cord, 2 the testis and 1 the tunica vaginalis, were all treated by radical orchiectomy. Pathologically, 2 cases were classified as stage I, 1 as stage II and 2 as stage IV. Postoperatively, 2 of the patients received chemotherapy and the other 3 refused adjunctive therapy. The patients were followed up for 6, 12, 18 and 28 months, respectively. Four of them remained free from relapse and metastasis, and 1 stage IV patient died of multiple metastasis at 6 months.Early diagnosis, radical orchiectomy and adjunctive chemo- or radio-therapy are effective means to the treatment of PER.

The viscosity and self-diffusion coefficients of C60 in the gas phase are reported, based upon a first-principles interaction potential. It is found that these transport coefficients increase monotonically with increasing temperature, but the calculated collision integrals, which are closely related to the transport coefficients, do not decrease monotonically with increasing temperature and exhibit a number of plateaus or the oscillating behavior. It is completely different from those of inert gases. This phenomenon should be ascribed to the interaction potential between C60 molecules. We confirm that the potential employed here does not behave like a Lennard-Jones (LJ) potential or Tang–Toennies (TT) potential and in turn a LJ-type or TT-type potential cannot describe exactly the interaction between C60 molecules.

The geometries, stabilities, and electronic and magnetic properties of Y(n)Al (n=1-14) clusters have been systematically investigated by using density functional theory with generalized gradient approximation. The growth pattern for different sized Y(n)Al (n=1-14) clusters is Al-substituted Y(n+1) clusters and it keeps the similar frameworks of the most stable Y(n+1) clusters except for Y(9)Al cluster. The Al atom substituted the surface atom of the Y(n+1) clusters for n9. Starting from n=9, the Al atom completely falls into the center of the Y-frame. The Al atom substituted the center atom of the Y(n+1) clusters to form the Al-encapsulated Y(n) geometries for n9. The calculated results manifest that doping of the Al atom contributes to strengthen the stabilities of the yttrium framework. In addition, the relative stability of Y(12)Al is the strongest among all different sized Y(n)Al clusters, which might stem from its highly symmetric geometry. Mulliken population analysis shows that the charges always transfer from Y atoms to Al atom in all different sized clusters. Doping of the Al atom decreases the average magnetic moments of most Y(n) clusters. Especially, the magnetic moment is completely quenched after doping Al in the Y(13), which is ascribed to the disappearance of the ininerant 4d electron spin exchange effect. Finally, the frontier orbitals properties of Y(n)Al are also discussed.

The geometries, stabilities, and electronic properties of TiSin (n=2-15) clusters with different spin configurations have been systematically investigated by using density-functional theory approach at B3LYP/LanL2DZ level. According to the optimum TiSin clusters, the equilibrium site of Ti atom gradually moves from convex to surface, and to a concave site as the number of Si atom increases from 2 to 15. When n=12, the Ti atom in TiSi12 completely falls into the center of the Si outer frame, forming metal-encapsulated Si cages, which can be explained by using 16-electron rule. On the basis of the optimized geometries, various energetic properties are calculated for the most stable isomers of TiSin clusters, including the average binding energy, the highest occupied molecular orbital and lowest unoccupied molecular orbital (HOMO-LUMO) gap, fragmentation energy, and the second-order difference of energy. It is found that at size n=6,8,12 the clusters are more stable than neighboring ones. According to the Mulliken charge population analysis, charges always transfer from Si atoms to Ti atom. Furthermore, the HOMO-LUMO gaps of the most stable TiSin clusters are usually smaller than those of Sin clusters.

We have investigated the stability, electronic, and magnetic properties of transition-metal-doped $M{\mathrm{B}}_{n}$ clusters ($M=\mathrm{Cr},\mathrm{Mn},\mathrm{Fe},\mathrm{Co},\mathrm{Ni}$, $n\ensuremath{\leqslant}7$) using first-principles density functional theory with generalized gradient approximation. The equilibrium structures of $M{\mathrm{B}}_{n}$ $(n\ensuremath{\leqslant}5)$ clusters can be obtained by directly adding $M$ atoms to the ${\mathrm{B}}_{n}$ clusters, while for $n=6$, hexagon or near-hexagon geometries with a boron atom at the center ring are regarded as the ground-state structures. $n=7$ marks the onset of three-dimensional geometries for $M{\mathrm{B}}_{n}$ clusters. According to the second-order energy differences, gaps between the highest occupied molecular orbital and lowest unoccupied molecular orbital and vertical ionization potentials, we can conclude that $\mathrm{Cr}{\mathrm{B}}_{4}$, $\mathrm{Cr}{\mathrm{B}}_{7}$, $\mathrm{Mn}{\mathrm{B}}_{3}$, $\mathrm{Fe}{\mathrm{B}}_{3}$, $\mathrm{Fe}{\mathrm{B}}_{5}$, $\mathrm{Fe}{\mathrm{B}}_{7}$, and $\mathrm{Co}{\mathrm{B}}_{7}$ possess relatively higher stabilities. The relative orientation between the magnetic moments of the $M$ atom and those of its neighboring B atoms mainly exhibits an antiferromagnetic alignment for $\mathrm{Cr}{\mathrm{B}}_{n}$, $\mathrm{Mn}{\mathrm{B}}_{n}$, and $\mathrm{Fe}{\mathrm{B}}_{n}$, while it mainly shows a ferromagnetic alignment for $\mathrm{Co}{\mathrm{B}}_{n}$ and $\mathrm{Ni}{\mathrm{B}}_{n}$ clusters.

In noncommutative space, we examine the problem of a noninteracting and harmonically trapped Bose-Einstein condensate, and derive a simple analytic expression for the effect of spatial noncommutativity on energy spectrum of the condensate. It indicates that the ground-state energy incorporating the spatial noncommutativity is reduced to a lower level, which depends upon the noncommutativity parameter $\theta$. The appeared gap between the noncommutative space and commutative one for the ground-state level of the condensate should be a signal of spatial noncommutativity., Comment: 7 pages; revtex4

The Moebius inversion pair potential has been employed, in combination with genetic algorithms, to predict the lowest-energy structures of the rare-earth metallic clusters La{sub N}, Ce{sub N}, and Pr{sub N} (N=3--20). Results are given for the symmetries, binding energies, nearest-neighbor distances of these clusters, and lowest-energy configurations of Ce{sub N} clusters. Also, the calculated second finite difference of the total energy shows that for three species elements, the 13-atom clusters with I{sub d} symmetry are particularly stable. Some minor peaks are also found at size N=4, 6, 11, and 15, which indicates that the corresponding clusters are relatively stable in structure. Present work points out a route to studying clusters.