Spectroscopy and molecule opacity investigation on excited states of SiS

The SiS molecule,which plays a significant role in space,has attracted a great deal of attention for many years.Due to complex interactions among its low-lying electronic states,precise information regarding the molecular structure of SiS is limited.To obtain accurate information about the structure of its excited states,the high-precision multireference configuration interaction(MRCI)method has been utilized.This method is used to calculate the potential energy curves(PECs)of the 18Λ–S states corresponding to the lowest dissociation limit of SiS.The core–valence correlation effect,Davidson’s correction and the scalar relativistic effect are also included to guarantee the precision of the MRCI calculation.Based on the calculated PECs,the spectroscopic constants of quasi-bound and bound electronic states are calculated and they are in accordance with previous experimental results.The transition dipole moments(TDMs)and dipole moments(DMs)are determined by the MRCI method.In addition,the abrupt variations of the DMs for the 1^(5)Σ^(+)and 2^(5)Σ^(+)states at the avoided crossing point are attributed to the variation of the electronic configuration.The opacity of SiS at a pressure of 100 atms is presented across a series of temperatures.With increasing temperature,the expanding population of excited states blurs the band boundaries.

Mutual neutralization in low-energy collisions of Na^(+)+H^(-)ions

The low-energy mutual neutralization(MN)reactions Na^(+)+H^(-)→Na(nl)+H have been studied by employing the full quantum-mechanical molecular-orbital close-coupling(QMOCC)method over a wide energy range of 10^(-3)-10^(3) e V/u.Total and state-selective cross sections have been investigated and compared with the available theoretical and experimental data,and the state-selective rate coefficients for the temperature range of 100-10000 K have been obtained.In the present work,all the necessary highly excited states are included,and the influences of rotational couplings and 10 active electrons are considered.It is found that in the energy below 10 e V/u,the Na(4s)state is the most dominant exit state with a contribution of approximately 78%to the branch fraction,which is in best agreement with the experimental data.For energies above 10 e V/u,the MN total cross section is larger than those obtained in other theoretical calculations and shows a slow decreasing trend because the main exit states change,when the energy is above 100 e V/u,the dominant exit state becomes the Na(3p)state,while the Na(4s)state becomes the third most important exit state.The datasets presented in this paper,including the potential energy curve,the radial and rotational couplings,the total and state-selective cross sections,are openly available at https://doi.org/10.57760/sciencedb.j00113.00112.

Theoretical study of electron-impact broadening for highly charged Ar XV ion lines

Spectral line widths produced by collisions between charged particles and emitters are of special interest for precise plasma spectroscopy.The highly charged Ar XV ion is demonstrated to have strong intrashell electron interactions,which manifest as an atomic system with many resonance structures,due to the quasi-degeneracy of orbital energies.In this paper we use the relativistic R-matrix method to investigate the electron-impact broadening of highly charged Ar XV ion spectral lines under the impact approximation.It is found that the results considering resonance structures are significantly different from those of the distorted wave approach.Furthermore,we propose a new empirical formula with a correction term to take into account the effect of resonances for electron-impact widths over a relatively wide range of plasma conditions.The corresponding fitting parameters of the new empirical formula for all 47 calculated transitions are also given with an estimated accuracy within 1%,which should be convenient for practical applications.The dataset that supported the findings of this study is available in Science Data Bank,with the link https://doi.org/10.57760/sciencedb.j00113.00101.

Dynamics and Thermodynamics of Porous HMX-like Material Under Shock

Strong shock may induce complex processes in porous materials.We use the newly developed material-point-methodto simulate such processes in an HMX-like material.To pick out relevant information,morphologicalcharacterization is used to treat with the temperature map.Via the Minkowski functional analysis the dynamics andthermodynamics of the shock wave reaction on porous HMX-like material are studied.The geometrical and topologicalproperties of the'hot-spots'are revealed.Numerical results indicate that,shocks in porous materials are not simplejump states as classically viewed,but rather are a complex sequence of compressions and rarefactions.They cover abroad spectrum of states.We can use coarse-grained description to the wave series.A threshold value of temperaturepresents a Turing pattern dynamical procedure.A higher porosity is generally preferred when the energetic materialneeds a higher temperature for initiation.The technique of data analysis can be used to other physical quantities,forexample,density,particle velocity,some specific stress,etc.From a series of studies along the line,one may get a largequantity of information for desiring the fabrication of material and choosing shock strength according to what needed isscattered or connected'hot-spots'.

Simulation Study of Shock Reaction on Porous Material

直接在吃惊下面多孔的材料当模特儿是一个复杂问题。我们经由最新发达的材料点方法调查如此的一个系统。吃惊力量和孔尺寸的效果是主要担心。为一样的孔， mean-void-size 的效果被检查。混合的本地骚乱和体积驱散是二重要机制让动能的转变加热，这被发现。当孔是很小的时，震惊的部分可以到达一个动态稳定的状态；在下游的部分的虚空反映背 rarefactive 波浪并且导致吝啬的密度和压力的细微摆动；为孔的一样的价值，更大的 mean-void-size 做更高吝啬的温度。当孔变得大时，水动力学数量在整个装载吃惊的过程期间与时间变化：在起始的阶段以后，吝啬的密度和压力减少，而是温度与更高的率增加。本地密度，压力，温度和粒子速度的分布通常是 non-Gaussian 并且与时间变化。变化的率取决于孔价值， mean-void-size 和吃惊力量。越强壮装载吃惊，孔完成越多 stronger。这个工作为快过程提供补充给实验并且在精力和动量交通揭示更基本的机制。

Experimental Study on Penetration and Perforation of Laminated Kevlar

The penetration behavior and perforation characteristics of Kevlar/Epoxy laminates with various thickness in quasi-static and ballistic perforation penetrated by steel projectiles with different noses are investigated. Quasi-static tests are conducted on MTS810 testing system. The results indicate that global deformation is the major mechanism of energy absorption and woven laminates exhibit larger energy dissipation than that of angle-plied laminates. Therefore, the woven laminates have better quasi-static penetration resistance. Ballistic tests with velocity of 200-700 m/s are executed by using a powder gun with 7.62 mm barrel. Comparing ballistic experimental results with those under quasi-static condition, both the perforation performance and the failure modes are related closely to the speed of penetrator. Quite different from quasi-static tests, ballistic tests indicate that thick angle-plied laminate targets are even better than woven laminates in resisting ballistic impact. It is observed that the damage zone of the laminate is localized highly with the increasing of the impact velocity and correspondingly, the failure modes are more manifold. The shape of projectile noses affects the impact resistance of laminated Kevlar significantly in the range of velocity around the ballistic limit..

Lévy Stable Distribution and [0, 2] Power Law Dependence of Acoustic Absorption on Frequency in Various Lossy Media

Absorption of acoustic wave propagation in a large variety of lossy media is characterized by an empirical power law function of frequency, α0｜ω＋^Ⅳ. It has long been noted that the exponent y ranges from 0 to 2 for diverse media. Recently, the present author J. Acoust. Soc. Am. 115 （2004） 1424] developed a fractional Laplacian wave equation to accurately model the power law diss^aation, which can be further reduced to the fractional Laplacian diffusion equation. The latter is known underlying the Lévy stable distribution theory. Consequently, the parameters y is found to be the Lévy stability index, which is known to be bounded within 0 〈 y ≤2. This finding first provides a theoretical explanation of empirical observations y ∈ [0, 2]. Statistically, the frequencydependent absorption can thus be understood a Lévy stable process, where the parameter y describes the fractal nature of attenuative media.

Disentangling the Effects of Thickness of the Neutron Skin and Symmetry Potential in Nucleon Induced Reactions on Sn Isotopes

对称精力的密度依赖和在质子(中子) 的中子皮肤的厚度的效果在 Sn 同位素上导致了反应借助于改进分子的动力学模型被调查。调查证明为质子的反应十字节的目标尺寸依赖在 Sn 同位素上导致了反应对对称精力和对目标的中子皮肤的厚度敏感的更少的密度依赖敏感原子核，而是那，因为中子在 Sn 同位素上导致了反应，它是对对称精力的密度依赖敏感、对目标原子核的中子皮肤的厚度敏感的更少。

Numerical Simulations on Buckling Failure of Preloaded Cylindrical Shell Irradiated by High Power Laser Beam

With finite-element software ANSYS 7.0 and simple thermal-mechanical coupling constitutive relations,the buckling failure of preloaded cylindrical shell irradiated by high power laser beam was studied by numerical simulations. The buckling mode and buckling critical loading were analysed for different preloading conditions. The influence of laser intensity, beam irradiation time, preloading conditions and geometric parameters of cylindrical shell on the buckling mode were discussed. The numerical results show that: ① the buckling deformation of the cylindrical shell was concentrated in the area of laser spot and the radial buckling was the main buckling mode, ② a linear relationship between the buckling eigenvalue and the maximum temperature at the center of laser spot was approached, ③ the buckling failure of cylindrical shell was attributed to the coupling effect of the material softening and the radial deformation in the laser spot, and hence to raise the stiffness of the material would enhance the ability for anti-irradiation of structure substantially..

Molecule opacity study on low-lying states of CS

CS molecule, which plays a key role in atmospheric and astrophysical circumstances, has drawn great attention for long time. Owing to its large state density, the detailed information of the electronic structure of CS is still lacking. In this work, the high-level MRCI+Q method is used to compute the potential energy curves, dipole moments and transition dipole moments of singlet and triplet states correlated with the lowest dissociation limit of CS, based on which high accurate vibration-rotation levels and spectroscopic constants of bound states are evaluated. The opacity of CS relevant to atmospheric circumstance is computed at a pressure of 100 atms for different temperatures. With the increase of temperature,band systems from different transitions mingle with each other, and band boundaries become blurred, which are originated from the increased population on vibrational excited states and electronic excited states at high temperature.

Electron excitation processes in low energy collisions of hydrogen-helium atoms

The electron excitation processes of H(1s)+He(1s^(2))→H(2s/2p)+He(1s^(2))are studied in impact energy range of 20-2000 e V/u by using the quantum-mechanical molecular orbital close-coupling(QMOCC)method.Total and state-selective cross sections have been obtained and compared with the available theoretical and experimental results.The results agree well with available measurements in the overlapping energy regions overall.The comparison of our results with other theoretical calculations further demonstrates the importance of considering a sufficient number of channels.The datasets presented in this paper,including the excitation cross sections,are openly available at https://www.doi.org/10.57760/sciencedb.j00113.00083.

Thermodynamic Properties of Sodium:A First-Principles Study

The Thermal expansion,Hugoniot state and 300 K isotherm of sodium have been calculated on the basis of:(i)the accurate calculations of 0 K total energies with the full-potential linearized augmented plane wave method within the generalized gradient approximation to exchange-correlational functional and(ii)the newly developed classical mean-field statistics where both the cold and thermal parts of the Helmholtz free-energy are entirely derived from the 0 K total energy.A quite satisfactory agreement between calculation and experiment has been observed.Our approach does not invoke any empirical parameter,which has long been a desirability on the field of material science.

M1 transition energy and rate in the ground configuration of Ag-like ions with 62 ≤ Z ≤ 94

Systematic calculations and assessments are performed for the magnetic dipole(M1)transition energies and rates between the ^(2)F^(o)_(5/2,7/2) levels in the ground configuration 4d104f along the Ag-like isoelectronic sequence with 62≤Z≤94 based on the second-order many-body perturbation theory implemented in the Flexible Atomic Code.The electron correlations,Breit interaction and quantum electrodynamics effects are taken into account in the present calculations.The accuracy and reliability of our results are evaluated through comprehensive comparisons with available measurements and other theoretical results.For transition energies,our results are in good agreement with the recent experimental data obtained from the electron beam ion traps within 0.18%.The maximum discrepancy between our results and those obtained with the large-scale multiconfiguration Dirac–Hartee–Fock calculations by Grumer et al.[Phys.Rev.A 89062501(2014)]is less than 0.13%along the isoelectronic sequence.Furthermore,the corresponding M1 transition rates are also reported.The present results can be used as the benchmark and useful for spectra simulation and diagnostics of astrophysical and fusion plasmas.

Highly Efficient Lattice Boltzmann Model for Compressible Fluids:Two-Dimensional Case

We present a highly efficient lattice Boltzmann model for simulating compressible Hows.This model isbased on the combination of an appropriate finite difference scheme,a 16-discrete-velocity model[Kataoka and Tsutahara,Phys.Rev.E 69(2004)035701(R)]and reasonable dispersion and dissipation terms.The dispersion term effectivelyreduces the oscillation at the discontinuity and enhances numerical precision.The dissipation term makes the new modelmore easily meet with the von Neumann stability condition.This model works for both high-speed and low-speed flowswith arbitrary specific-heat-ratio.With the new model simulation results for the well-known benchmark problems geta high accuracy compared with the analytic or experimental ones.The used benchmark tests include(i)Shock tubessuch as the Sod,Lax,Sjogreen,Colella explosion wave,and collision of two strong shocks,(ii)Regular and Mach shockreflections,and(iii)Shock wave reaction on cylindrical bubble problems.With a more realistic equation of state orfree-energy functional,the new model has the potential tostudy the complex procedure of shock wave reaction on porousmaterials.

Comparison Study on Characteristic Regimes in Shocked Porous Materials

我们在其机械性质盖住一个宽范围的震惊的多孔的材料在典型政体上执行比较研究。经由 Minkowski 功能的分析，不同材料可以在装载吃惊的过程显示出典型政体的一样的部分尺寸，这被发现，就算一个人使用一样的阀值价值定义那些政体。在有更大的起始的产量的材料的典型政体是驱散的更多。为固定吃惊力量，在那里存在冲击波反应与贡献最大的塑料工作的材料力量。与吃惊力量减少，这材料力量变得更小。这些观察可以为新材料图案介绍有用指示。

Multiple-Relaxation-Time Lattice Boltzmann Approach to Richtmyer-Meshkov Instability

The aims of the present paper are twofold.At first,we further study the Multiple-Relaxation-Time (MRT) Lattice Boltzmann (LB) model proposed in [Europhys.Lett.90 (2010) 54003].We discuss the reason why the Gram-Schmidt orthogonalization procedure is not needed in the construction of transformation matrix M;point out a reason why the Kataoka-Tsutahara model [Phys.Rev.E 69 (2004) 035701(R)] is only valid in subsonic Rows.The von Neumann stability analysis is performed.Secondly,we carry out a preliminary quantitative study on the Richtmyer-Meshkov instability using the proposed MRT LB model.When a shook wave travels from a fight medium to a heavy one,the simulated growth rate is in qualitative agreement with the perturbation model by Zhang-Sohn.It is about half of the predicted value by the impulsive model and is closer to the experimental result.When the shock wave travels from a heavy medium to a light one,our simulation results are also consistent with physical analysis.

Three-Dimensional Lattice Boltzmann Model for High-Speed Compressible Flows

A highly efficient three-dimensional (3D) Lattice Boltzmann (LB) model for high-speed compressible Sowsis proposed.This model is developed from the original one by Kataoka and Tsutahara [Phys.Rev.E 69 (2004) 056702].The convection term is discretized by the Non-oscillatory, containing No free parameters and Dissipative (NND) scheme,which effectively damps oscillations at discontinuities.To be more consistent with the kinetic theory of viscosity and tofurther improve the numerical stability, an additional dissipation term is introduced.Model parameters are chosen insuch a way that the von Neumann stability criterion is satisfied.The new model is validated by well-known benchmarks,(i) Riemann problems, including the problem with Lax shock tube and a newly designed shock tube problem with highMach number; (ii) reaction of shock wave on droplet or bubble.Good agreements are obtained between LB results andexact ones or previously reported solutions.The model is capable of simulating flows from subsonic to supersonic andcapturing jumps resulted from shock waves.

Flux Limiter Lattice Boltzmann for Compressible Flows

In this paper,a new flux limiter scheme with the splitting technique is successfully incorporated into amultiple-relaxation-time lattice Boltzmann (LB) model for shacked compressible Hows.The proposed flux limiter schemeis efficient in decreasing the artificial oscillations and numerical diffusion around the interface.Due to the kinetic nature,some interface problems being difficult to handle at the macroscopic level can be modeled more naturally through theLB method.Numerical simulations for the Richtmyer-Meshkov instability show that with the new model the computedinterfaces are smoother and more consistent with physical analysis.The growth rates of bubble and spike present asatisfying agreement with the theoretical predictions and other numerical simulations.

Flux Limiter Lattice Boltzmann Scheme Approach to Compressible Flows with Flexible Specific-Heat Ratio and Prandtl Number

We further develop the lattice Boltzmann (LB) model [Physica A 382 (2007) 502] for compressible flows fromtwo aspects.Firstly,we modify the Bhatnagar-Gross-Krook (BGK) collision term in the LB equation,which makes themodel suitable for simulating flows with different Prandtl numbers.Secondly,the flux limiter finite difference (FLFD)scheme is employed to calculate the convection term of the LB equation,which makes the unphysical oscillations atdiscontinuities be effectively suppressed and the numerical dissipations be significantly diminished.The proposed modelis validated by recovering results of some well-known benchmarks,including (i) The thermal Couette Row;(ii) One- andtwo-dimensional Riemann problems.Good agreements are obtained between LB results and the exact ones or previouslyreported solutions.The Rexibility,together with the high accuracy of the new model,endows the proposed modelconsiderable potential for tracking some long-standing problems and for investigating nonlinear nonequilibrium complexsystems.

Electron-impact ionization cross section calculations for lithium-like ions

The electron-impact ionization of lithium-like ions C^(3+),N^(4+),O^(5+),Ne^(7+),and Fe2^(3+)is studied using a combination of two-potential distorted-wave and R-matrix methods with a relativistic correction.Total cross sections are computed for incident energies from 1 to 10 times of ionization energy and better agreements with the experimental results are obtained in comparison with the theoretical data available.It is found that the indirect ionization processes become significant for the incident energy larger than about four times of the ionization energy.Contributions from the exchange effects along the isoelectronic sequence are also discussed and found to be important.The present method can be used to obtain systematic ionization cross sections for highly charged ions across a wide incident energy range.