Calculation of the fine-structure parameters for np 5 n′f configurations of rare-gas atoms

In the single-configuration approximation, fine-structure parameters are calculated semiempirically in the intermediate coupling scheme for the configurations 2_p ⁵ nf(n=4–6) of NeI, 3p ⁵ nf(n=4–7) of ArI, and 4p ⁵4f of KrI. With the fine-structure parameters obtained, the coefficients of expansion of the wave functions in basis functions of the LS-coupling scheme and the gyromagnetic ratios are calculated. To the authors’ knowledge, analogous data are absent in the literature. The correctness of the fine-structure parameters obtained is confirmed by values of the fine-splitting constant, which is well known for other configurations of rare-gas atoms with an almost filled p shell.     

Nonlinear gain and dispersion in the four-level Λ-type system

The nonlinear gain and dispersion spectra of a four-level Λ-type system, which driven by a weak probe field and coupling field, is investigated. Using the perturbation method, third-order perturbation iterative solutions of the steady density matrix equations are obtained. We find that effect of the SGC on the nonlinear gain and dispersion are negligible. At the resonant coupling, nonlinear dispersion spectra of the two transition paths are symmetrical about a line, but the nonlinear absorption spectra are symmetrical about a point. The degeneration of the two lower states greatly modifies the nonlinear gain and dispersion spectra.     

Calculation of scattering parameters for ultracold 6Li-TLi elastic collisions＊

This paper theoretically studies the elastic scattering properties in a mixture of 6Li and 7Li atoms at cold and ultracold temperatures. Based on the constructed accurate interatomic potential of the triplet state for 6Li7Li mixture by the mass scaling method, it calculates the interspecies s-wave scattering lengths and the p-wave scattering lengths by the variable phase method and the semiclassical method, respectively. The scattering length is in good agreement with the experiment. The partial-wave and total cross sections are also calculated and a rich resonance structure is found.     

Calculation of scattering parameters for ultracold ~6 Li-~7 Li elastic collisions

This paper theoretically studies the elastic scattering properties in a mixture of 6 Li and 7 Li atoms at cold and ultracold temperatures.Based on the constructed accurate interatomic potential of the triplet state for 6 Li 7 Li mixture by the mass scaling method,it calculates the interspecies s-wave scattering lengths and the p-wave scattering lengths by the variable phase method and the semiclassical method,respectively.The scattering length is in good agreement with the experiment.The partial-wave and total cross sections are also calculated and a rich resonance structure is found.     

Calculation of the elastic scattering properties for cold and ultracold 39K atoms in a triplet state

The elastic scattering properties for collisions between cold and ultracold 39K atoms in a triplet state are investigated. Based on the recent theoretical and experimental results, the improved hybrid potential is presented for a triplet α3∑u^＋ ground state of K2. Our calculated value of the s-wave scattering length a by using the Numerov method for the triplet state is 79.578α0 and found to be in good agreement with the previous ones. The numbers of bound states are supported by the molecular potential. Pronounced shape resonances appear for the l = 3 partial waves for the α3∑u^＋ state. Furthermore, the s-wave scattering cross section, the total cross section and energy positions of shape resonances for the α3∑u^＋ state are calculated.     

Higher threshold parameters in ππ scattering

A family of threshold parameters which probe the stability of chiral predictions is considered. The relevant criteria for the choice of threshold parameters are discussed. Sum rules for these quantities are derived from dispersion relations and evaluated from effective range formulae. Good agreement with two-loop chiral estimates for many of these quantities is found and interesting discrepancies are discussed.     

Calculation of vibrations of the H-bonds and electrooptical parameters of the F(HF)2]− complex

The problem of calculating the vibrations of the F(HF)₂]^? complex with hydrogen bonds is considered with allowance for the anharmonicity and interaction of motions in different degrees of freedom. A systematic solution of this problem is proposed which consists in separating the total vibrational system into subsystems, obtaining sufficiently exact vibrational wave functions of subsystems, and expanding the vibrational wave functions of the total system in basis functions constructed from the wave functions of subsystems. At the first stage of our study, the stretching and bending modes of two F...HF hydrogen bonds are considered with the use of an exact kinetic energy operator and a nonempirical three-dimensional potential energy surface. It is shown that these vibrational modes of the complex are characterized by significant mechanical and electric anharmonicities. The calculated values of frequencies of the symmetric and antisymmetric vibrations of hydrogen bonds are in good agreement with the experimental findings.     

Accurate calculations of the 18 Λ-S states and 50 Ω states of PO+ cation: potential energy curves and spectroscopic parameters including the spin-orbit coupling effect

The potential energy curves (PECs) of 5 Ω states generated from the 18 Λ-S states (X ¹ Σ ⁺, A¹Σ^?, 1¹ Δ, 1¹ Π, 2¹Σ⁺, 2¹ Π, a ³ Σ ⁺, 1³ Δ, 1³ Π, 1³Σ^?, 2³Σ⁺, 2³ Π, 1⁵Σ⁺, 1⁵ Π 2⁵ Π, 1⁵Σ^?, 2⁵Σ⁺ and 1⁵ Δ) of PO⁺ cation are studied for the first time for internuclear separations from about 0.08 to 1.0 nm. Of these Λ-S states, only the 2⁵Σ⁺ and 1⁵ Δ are the replusive ones. The a ³ Σ ⁺, 2³Σ⁺, 1⁵Σ^?, 2³ Π, 1³ Δ, 2⁵Σ⁺ , and 1⁵ Δ are the inverted states with the spin-orbit coupling effect included. The 1¹ Π, 1³ Π, 1⁵ Π and 2³ Π states possess the double well. The 1⁵Σ^?, 2¹ Π and 2⁵ Π states and the second wells of 1¹ Π, 1³ Π, 2³ Π and 1⁵ Π states are the rather weakly bound states. The PEC calculations are performed by the CASSCF method, which is followed by the icMRCI approach with Davidson correction in combination with the aug-cc-pV6Z basis set. Core-valence correlation and scalar relativistic corrections are included at the same time. The spin-orbit coupling effect is accounted for. All the PECs are extrapolated to the complete basis set limit. The spectroscopic parameters are evaluated for all the Λ-S and Ω bound states, and compared with the measurements and other theoretical results. Fair agreement is found between the present spectroscopic parameters and the measurements. The vibrational properties are evaluated for the weakly bound states. The effect of spin-orbit coupling on the spectroscopic parameters is discussed. The results reported in this paper can be expected to be reliable predicted ones.     

Calculation of the surface tension and the surface energy of Lennard–Jones fluids from the radial distribution function in the interface zone

A detailed study is presented of the calculation of the surface tension and the surface energy of Lennard–Jones fluids from the radial distribution function and the density profile. To do so, a modification is made to Lekner and Henderson's statistical mechanics approach by introducing two simple analytical expressions for the radial distribution function of the interface zone. In these expressions the radial distribution functions of the liquid and vapour phases are weighted via step or exponential variations. The well- known exponential model for the density profile in the interface zone is considered. Finally, results are compared with values from experiment, from computer simulation and from relevant theoretical developments. It is shown that the use of the proposed radial distribution function in the interface zone represents a significant improvement in applying Lekner and Henderson's approach.     

Characteristics of holographic scattering and its application in determining kinetic parameters in PQ-PMMA photopolymer

This paper characterizes holographic scattering and demonstrates its application in determining the kinetic parameters in materials with high transmittance and strong holographic scattering like phenanthrenequinone doped poly (methyl methacrylate) (PQ-PMMA). We define a polymerization rate parameter which can be determined by the temporal evolution of the scattering losses. Two basic kinetic parameters, quantum yield and molar-absorption coefficient, are obtained by nonlinear fitting the curve of the polymerization rate parameter as a function of the thickness, which are 1.9×10⁻⁶ mol/einstein and 2.1×10⁴ cm²/mol for a wavelength of 532 nm respectively. These results improve the understanding of photochemical behaviors and allow us to describe the grating formation in the photopolymer reasonably.     

Impurity effects of the Λ hyperon in the hypernuclear systems Λ25Mg and Λ29Si

Based on the beyond-mean-field Skyrme-Hartree-Fock model,impurity effects of the Λ hyperon in the hypernuclear systems Λ25Mg and Λ29Si are investigated,respecti...     

T → d+n vertex function and its correlation with the triton binding energy and with the doublet nd scattering length

The asymptotic normalization constant C _T ² for the triton is calculated within a two-body model for potentials characterized by a Yukawa-type short-distance behavior and the long-distance asymptotic behavior V(r)→const×r ^?νexp(?μr), where ν=0, 1, 2. It is shown that C _T ² decreases monotonically with increasing ν and that it smoothly decreases with increasing a ₂ κ, where a ₂ is the doublet scattering length and κ is the triton wave number. This behavior is consistent with effective-range theory taking into account the pole of κ cot δ and with the general trend of Faddeev calculations. It is established, however, that some calculations reported previously and performed on the basis of the N/D method yield, on the contrary, a sharp growth of C _T ² . The results of the calculation of the form factor for the T → d+n vertex are compared with the results of the well-known three-body calculation.     

Study on the optical system for the record of the pulsed acoustic field and the scattering of the cylindrical-like objects buried in underwater sand

11尬roductlon For the vlsuallzatlon and the studies of the physical properties of acoustic ield;the schlierentechnique was the most useful for the co尬Inuous waves[1,2].ReceNwars,the shadowgraphmode was appeared for the recording of＊theing acoustic pulse[3-p].Although the shadowgr地hmode Is used more frequently In experimental fluid dynamics[6],In the irst part of this paper;the response of＊these opticall扯enslty of＊the recorded acoustic pulse related to the acousticpressure gradlem Is st…     

Photon scattering on quasi-free neutrons in the reaction γd→γ′np and neutron polarizabilities

The possibility to obtain information on n scattering at intermediate energies from the reaction dnp is analyzed. To this aim, the differential cross sectiond ³ /d ,d _n dE _n and the scattering asymmetry with linearly polarized photons are calculated at photon energies 100 to 400 MeV in the diagrammatic approach. The pole diagrams of the impulse approximation are evaluated with realistic n and p scattering amplitudes. One-loop diagrams withnp rescattering in the final state and with meson-exchange and isobar currents are taken into account as well. The main contribution to the differential cross sectiond ³ /d ,d _n dE _n in the kinematics of quasi-free n scattering arises from the neutron pole diagram. The correction due to other diagrams is typically –30% to –10% and decreases with increasing photon energy and momentum transfer. The sensitivity of the cross sections to the magnitude of the neutron electric polarizability and to the sign of the ⁰2 decay constant is demonstrated.     

Symmetry energy of the nucleus in the relativistic Thomas–Fermi approach with density-dependent parameters

We introduce an inhomogeneous term, f(t,x), into the right-hand side of the usual Burgers equation and examine the resulting equation for those functions which admit at least one Lie point symmetry. For those functions f(t,x) which depend nontrivially on both t and x, we find that there is just one symmetry. If f is a function of only x, there are three symmetries with the algebra s l(2,R). When f is a function of only t, there are five symmetries with the algebra s l(2,R) ⊕ _s 2A ₁. In all the cases, the Burgers equation is reduced to the equation for a linear oscillator with nonconstant coefficient.     

New effects in low energy scattering of pµ atoms

Strong solid state effects in low energy scattering of pμ atoms in solid hydrogen are reported and analyzed. Such effects have been observed in TRIUMF experiment E742 where muons are stopped in thin frozen (3 K) layers of hydrogen. Emission of low energy pμ atoms from the hydrogen layer into adjacent vacuum was much higher than expected, based on calculations which ignored the solid nature of hydrogen. Monte Carlo simulations, performed using the scattering cross-sections with solid state effects taken into account, show the important role of the coherent elastic Bragg scattering in the diffusion of pμ atoms. For pμ energies lower than the Bragg cut-off limit (∼2 meV) the total scattering cross-section falls by several orders of magnitude, the hydrogen target becomes transparent and the emission of cold pμ atoms takes place. This revised version was published online in August 2006 with corrections to the Cover Date.     

Accurate potential energy curves and spectroscopic properties of the 27 Λ-S states and 73 Ω states of the PO radical

The potential energy curves (PECs) were calculated for the 27 Λ-S states and 73 Ω states of PO radical. The calculations were done using the CASSCF method, which was followed by the internally contracted multireference configuration interaction (icMRCI) approach. To improve the quality of PECs, core-valence correlation and scalar relativistic corrections as well as Davidson correction were included. Of the 27 Λ-S states, the 1⁶Σ⁺ state was repulsive at any case. The 1⁴Φ and 1⁶Π states were bound, but they became repulsive with the spin-orbit coupling (SOC) effect accounted for. The 3⁴Σ⁺, a⁴Π, C′²Δ, D′²Π, 1⁴Δ, 1²Φ, 1⁶Σ⁺ and 1⁶Π states were inverted with the SOC effect included. The F²Σ⁺ state had double wells. The avoided crossings existed between the B²Σ⁺ and F²Σ⁺ states, the F²Σ⁺ and 3²Σ⁺ states, the C′²Δ and 2²Δ states, the 1⁴Δ and 2⁴Δ states, the 2⁴Δ and 3⁴Δ states, the 2⁴Π and 3⁴Π states and the 3⁴Π and 4⁴Π states. The c⁴Σ⁺, 2⁴Σ⁺, 3⁴Σ⁺, 3⁴Π, 4⁴Π, 5⁴Π, 3⁴Δ, 1⁴Φ and 1⁶Π states were weakly bound, which well depths were within several hundred cm^?1. The spectroscopic parameters were derived. The SOC effect on the spectroscopic properties was evaluated. The spectroscopic results obtained here could be expected to be reliably predicted ones.     

Analysis of data on proton-proton scattering in the energy range 100–1300 MeV

The results of a partial-wave analysis of data on proton-proton interaction in the energy range 100–1300 MeV are presented. The real parts of phase shifts were found for states of orbital angular momentum up to L = 9, while their imaginary parts were determined for states of orbital angular momentum up to L = 5. The sixth parameter of the S matrix was introduced in order to describe states of total angular momentum J = 2 and 4. The inelasticity thresholds were chosen individually for each state and were found to be substantially different from one another. The resulting solution was characterized by χ ² = 1.155 per point in the case where the number of experimental data was 12 841 and by a large imaginary part of the phase shift in the ³ P ₂-wave state at the edge of the energy range. Special features of the interaction in orbital states are discussed along with the energy dependence of integrated amplitudes and amplitudes of the scattering matrix at zero angle.     

Time and energy dependent dynamics of the STM tip — graphene system

Probability current and probability density of wave packets was calculated by solving the three dimensional time-dependent Schrödinger equation for a local potential model of the scanning tunneling microscope (STM) tip — graphene system. Geometrical and electronic structure effects of the three dimensional tunneling process are identified by studying three models of increasing complexity: a jellium half space, a narrow jellium sheet, and a local one electron pseudopotential. It was found that some of the key characteristics of the STM tip — graphene tunneling process are already present at the simple jellium models. In the STM tip — jellium half space system the direction of the momentum does not change during the tunneling event, hence this setup is characterised by introducing an effective distance. For the STM tip — narrow jellium sheet system the direction of the momentum is changed from vertical to horizontal during the tunneling event. The wave packet preferentially tunnels into the bound state of the jellium sheet. For the atomistic model of the graphene sheet an anisotropic spreading of the wave packet was found for hot electrons. This may open new opportunities to build carbon based nanoelectronic devices.