The effect of correlation energy (MP2) on computed vibrational frequencies

The IR frequencies of cyclopropene and methylenecyclopropene were computed with inclusion of correlation (MP2 /6-31G*). These along with those of ethylene obtained earlier by Pople were compared with SCF results (DZ + P). It was found that the MP 2 frequencies agreed better with experiment, but that the order of the bands remained the same as those computed without correlation.     

Local connectivity functions on arcwise connected spaces and certain continua

Types of spaces are given on which every local connectivity function is a connectivity function, a connected function, or a Darboux function. A complete determination such spaces is obtained when the spaces are assumed to be arc-like continua or circle-like continua. Results provide answers to a question asked by Stallings.     

关于比较椭圆流理论计算和实验估计的难处

Elliptic flow is easy to compute in hydrodynamics. However experimentally it is obtained in an indirect way. The question we address in this paper is how comparable are these two approaches. For both cases, our study is done using the hydrodynamical code NeXSPheRIO and simulating nuclear collisions at RHIC.     

Dispersion model of cesium-137 in surface oceanic waters

The¹³⁷Cs radionuclide dispersion in the marine environment through the compartmental model is reported. The model simulates the surface water contamination caused by routine or accidental radionuclide releases. For the simulation the OCEAN program was applied in the North Sea, near to Sellafield and adjacent areas, based on published transfer coefficient data. The results are in good agreement with the literature and the model developed can be applied to the brazilian coastal regions.     

Same-sign dileptons as a signature for heavy Majorana neutrinos in hadron-hadron collisions

We discuss the possibility of same-sign dileptons as a signature for Majorana neutrinos. The production mechanism is given by a single heavy neutrino production and decay pp → l^±NX → l^±l^±X′. Cross section and distributions are presented for the LHC energies.     

Pump-depleting four-wave mixing in supercontinuum-generating microstructure fibers

Four-wave mixing processes are shown to provide a high efficiency of non-linear optical frequency conversion and spectral transformation of ultrashort pulses in supercontinuum-generating microstructure fibers. Pump-depleting conversion of 800-nm radiation to the spectral range around 500 nm is achieved by phase-matching the parametric four-wave mixing process for 80-fs Ti:sapphire-laser pulses. The ways to use microstructure fibers for generating frequency-tunable radiation through four-wave mixing with the maximum efficiency of pump-field frequency conversion are discussed. PACS 42.65.Wi; 42.81.Qb     

Laser ablation and desorption from calcite from ultraviolet to mid-infrared wavelengths

3 ) at wavelengths ranging from the ultraviolet to the mid-infrared, including a Nd:YAG laser operated at the fundamental, second and third harmonics, and a tunable infrared free-electron laser (wavelength range 2.5–8 μm). The threshold for ablation and the topography of the irradiated spot were characterized by scanning electron microscopy. A clear indication of two distinct excitation mechanisms was observed, namely, cracks and fractures followed by exfoliation at ultraviolet to near-infrared wavelengths, in contrast to evaporative holes and scattered droplets in the mid-infrared. Plume emission/absorption spectroscopy, plume transmission and photoacoustic beam deflection were used to characterize the ablation plasma. The composition of atoms, molecules, or particles in the ablation plumes also has a distinctive variation as a function of the wavelength. The excitation mechanisms leading to ablation appear to be defect activation at ultraviolet to near-infrared wavelengths, molecular impurity absorption and resonant vibrational absorption of the calcite at mid-infrared. Received: 5 December 1996/Accepted: 6 January 1997     

Cyclic polytopes, hyperplanes, and Gray codes

We consider cyclic d-polytopes P that are realizable with vertices on the moment curve $M_d:t\longrightarrow (t,t^2,\ldots,t^d)$ of order $d\geq 3$. A hyperplane H bisects a j-face of P if H meets its relative interior. For $\ell\geq 1$, we investigate the maximum number of vertices that P can have so that for some $\ell$ hyperplanes, each j-face of P is bisected by one of the hyperplanes. For $\ell > 1$, the problem translates to the existence of certain codes, or equivalently, certain paths on the cube $\{0,1\}^\ell$.