CAS-MCSCF Study on the Ground State of the Ditungsten Molecule(W_2)

Complete active space multiconfiguration self-consisten-field (CAS-MCSCF)calculations are carried out on the ground stae() of W_2. The spectroscopic properties(Re=2.078A. De=4.224eV and ωe=304.3cm-1) and the poential energy curve of the state are reported. The calculations predict the W-W bond order of 5.02.

Effective mass of the ground state of the strong-coupling exciton in a quantum well

The properties of the effective mass of the ground state of the exciton, for which the electron (hole) is strongly coupled with interface-optical (IO) phonons but weakly coupled with bulk-longitudinal-optical (LO) phonons in a quantum well, are studied by means of Tokuda’s improved linear combination operator and a modified second Lee-Low-Pines transformation method. The results indicate that the contributions of the interaction between the electron (hole) and the different phonon branches to the effective mass are greatly different, and change with the well width and the relative position between the electron and the hole.

Probing Structure, Thermochemistry, Electron Affinity and Magnetic Moment of Dysprosium-doped Silicon Clusters DySi_n(n = 3～10) and Their Anions with Double-hybrid Density Functional Theory

The equilibrium geometries, electronic structures and electronic properties including adiabatic electron affinity（AEA）, vertical detachment energy（VDE）, simulated photoelectron spectroscopy, HOMO-LUMO gap, charge transfer, and magnetic moment for DySi_n（n = 3~10） clusters and their anions were systematically investigated by using the ABCluster global search technique combined with the B3 LYP and B2 PLYP density functional methods. The results showed that the lowest energy structure of neutral DySi_n（n = 3~10） can be regarded as substituting a Si atom of the ground state structure of Si_（n＋1） with a Dy atom. For anions, the extra electron effect on the structure is significant. Starting from n = 6, the lowest energy structures of DySi_n~？（n = 3~10） differ from those of neutral. The ground state is quintuplet electronic state for DySi_n（n = 3~10） excluding DySi_4 and DySi_9, which is a septet electronic state. For anions, the ground state is a sextuplet electronic state. The reliable AEA and VDE of DySi_n（n = 3~10） are reported. Analyses of HOMO-LUMO gaps indicated that doping Dy atom to silicon clusters can improve significantly their photochemical reactivity, especially for DySi_9. Analyses of NPA revealed that the 4 f electrons of Dy in DySi_4, DySi_9, and DySi_n~？ with n = 4 and 6~10 participate in bonding. That is, DySi_nbelongs to the AB type. The 4 f electrons of Dy atom provide substantially the total magnetic moments for DySi_n and their anions. The dissociation energies of Ln（Ln = Pr, Sm, Eu, Gd, Ho, and Dy） fromLn Sin and their anions were evaluated to examine the relative stabilities.

Sudden birth and sudden death of thermal fidelity in a two-qubit system

We study the energy level crossing and the thermal fidelity in a two-qubit system with the presence of a transverse inhomogeneous magnetic field.With the help of contour plots,we clearly identify the ground states of the system in different regions of parameter space,and discuss the corresponding energy level crossing.The fidelity between the ground state of the system and the state of the system at temperature T is calculated.The result shows that the fidelity is very sensitive to the magnetic field anisotropic factor,indicating that this factor may be used as a controller of the fidelity.The influence of the Yangian transition operators on the fidelity of the system is discussed.We find that the Yangian operators can change the fidelity dramatically and give rise to sudden birth and sudden death phenomena of the thermal fidelity.This makes the corresponding Yangian operators possible candidates for switchers to turn the fidelity on and off.

Properties of polaron in a triangular quantum well induced by the Rashba effect

The properties of the weakly-coupling bound polaron, considering an influence of Rashba effect, which is brought about by the spin-orbit （SO） interaction, in an semiconductor triangular quantum well （TQW）, have been studied by using the linear combination operator and the unitary transformation methods. We obtain an expression for the ground state energy of the weak-coupling and bound polaron in a TQW as a function of the coupling constant, Coulomb bound potential, and the electron areal density. Our numerical resuks show that the ground state energy of the polaron is composed of four parts, one part is caused by the electrons＇ own energy, the second part is caused by the Rashba effect, the third part occurs because of the Coulomb bound potential, and the last term is induced by the interaction between the electrons and LO phonons. The interactions between the orbit and the spin with different directions have different effects on the ground state energy of the polaron.

Structural and Electronic Properties of Lutetium Doped Germanium Clusters LuGen^((+/0/-))(n=6~19):A Density Functional Theory Investigation

Structural growth mechanism,energetics,and electronic properties of cationic,neutral,and anionic lutetium doped germanium cluster LuGen^((+/0/-))(n=6~19)were comprehensively studied by the ABCluster unbiased global search technique with a hybrid density functional theory approach.Compared to the experimental PES,the anion evolution of structure can be clearly defined as four-phase:from the adsorbed to the link structure,then to the half cage motif,and finally to the endohedral structure.The results revealed that the LuGe16-as Frank-Kasper structure with high symmetry of Td can greatly enhance the stabilities.Doped structures have shown thermodynamic stability and appropriate energy gap.These materials are suitable semiconductors.Various approaches,including quasi-spherical geometry with closed-shell model,aromaticity,UV-Vis spectra,density of states(DOS)and partial density of states(PDOS)were applied to further support the results.