First-principles study on scanning tunneling microscopy images of hydrogen-terminated Si(110) surfaces

Scanning tunneling microscopy images of hydrogen-terminated Si(110) surfaces are studied using first-principles calculations. Our results show that the calculated filled-state images and local density of states are consistent with recent experimental results, and the empty-state images appear significantly different from the filled-state ones. To elucidate the origin of this difference, we examined in detail the local density of states, which affects the images, and found that the bonding and antibonding states of surface silicon atoms largely affect the difference between the filled- and empty-state images.Comment: 4 pages, and 4 figure

Deformed Base Antisymmetrized Molecular Dynamics and its Application to ^{20}Ne

A new theoretical framework named as deformed base antisymmetrized molecular dynamics that uses the localized triaxially deformed Gaussian as the single particle wave packet is presented. The model space enables us to describe sufficiently well the deformed mean-field structure as well as the cluster structure and their mixed structure within the same framework. The improvement over the original version of the antisymmetrized molecular dynamics which uses the spherical Gaussian is verified by the application to $^{20}{\rm Ne}$ nucleus. The almost pure $\alpha + ^{16}{\rm O_{g.s}}$ cluster structure of the $K^\pi$=$0^-$ band, the distortion of the cluster structure in the $K^\pi$=$0^+_1$ band and the dominance of the deformed mean-field structure of the $K^\pi$=$2^-$ band are confirmed and their observed properties are reproduced. Especially, the intra-band E2 transition probabilities in $K^\pi$=$0^+_1$ and $2^-$ bands are reproduced without any effective charge. Since it has been long known that the pure $\alpha + ^{16}{\rm O}_{g.s.}$ cluster model underestimates the intra-band $E2$ transitions in the $K^\pi$=$0^+_1$ band by about 30%, we consider that this success is due to the sufficient description of the deformed mean-field structure in addition to the cluster structure by the present framework. From the successful description of $^{20}{\rm Ne}$, we expect that the present framework presents us with a powerful approach for the study of the coexistence and interplay of the mean-field structure and the cluster structure

Effect of a Transverse D.C. Electric Fields on Electrostatic lon-Cyclotron Wave Instability

Abstract The temporal evolution of the current-driven electrostatic ion-cyclotron (CDEIC) instability is investigated in presence of a transverse d.c. electric fields in a collisional magnetized plasma. The growth rate of the instability has the largest value at the mode frequency for the appropriate magnetic field (where the effect of a transverse d.c. electric fields is larger) when the electron drift velocity is less than the critical value for the CDEIC instability. The growth rate is also a sensitive function of electron collision frequency

An SU(N) Mott insulator of an atomic Fermi gas realized by large-spin Pomeranchuk cooling

The Hubbard model, containing only the minimum ingredients of nearest neighbor hopping and on-site interaction for correlated electrons, has succeeded in accounting for diverse phenomena observed in solid-state materials. One of the interesting extensions is to enlarge its spin symmetry to SU(N>2), which is closely related to systems with orbital degeneracy. Here we report a successful formation of the SU(6) symmetric Mott insulator state with an atomic Fermi gas of ytterbium (173Yb) in a three-dimensional optical lattice. Besides the suppression of compressibility and the existence of charge excitation gap which characterize a Mott insulating phase, we reveal an important difference between the cases of SU(6) and SU(2) in the achievable temperature as the consequence of different entropy carried by an isolated spin. This is analogous to Pomeranchuk cooling in solid 3He and will be helpful for investigating exotic quantum phases of SU(N) Hubbard system at extremely low temperatures.Comment: 20 pages, 6 figures, to appear in Nature Physic