Aharonov–Bohm effect for bound states on spin-0 massive charged particles in a Gödel-type space–time with Coulomb potential

In this paper, we investigate the relativistic quantum dynamics of spin-0 massive charged particles in a Gödel-type space–time with electromagnetic interactions. We derive the radial wave equation of the Klein–Gordon equation with an internal magnetic flux field and Coulomb-type potential in the Som–Raychaudhuri space–time with cosmic string. We solve this equation and analyze the analog effect in relation to the Aharonov–Bohm effect for bound states.     

Superperiodicity,chaos and coexisting orbits of ion-acoustic waves in a four-component nonextensive plasma

Superperiodicity, chaos and coexisting orbits of ion-acoustic waves (IAWs) are studied in a multi-component plasma consisting of fluid ions, q -nonextensive cold and hot electrons and Maxwellian hot positrons. The significant impacts of the system parameters on superperiodic and nonlinear periodic IAWs are presented. Considering an external periodic perturbation various types of quasiperiodic and chaotic features for IAWs are studied in different parametric ranges through time series’ plots, phase spaces and Lyapunov exponents. It has been observed that there exist some coexisting orbits for IAWs. Coexisting orbits for IAWs in a classical electron–positron–ion plasma system are reported.     

The structural,electronic and magnetic properties of Ag4M and Ag4MCO (M = Sc–Zn) clusters

The structures, spectra and electronic and magnetic properties of Ag₄M and Ag₄MCO (M?=?Sc–Zn) clusters have been studied using density functional theory and CALYPSO structure searching method. Structural searches show that M atoms except Zn tend to occupy the highest coordination position in the ground state Ag₄M and Ag₄MCO clusters. Carbon monoxide is most easily adsorbed on Ag atom of Ag₄Zn and M atom of other Ag₄M. Infrared and Raman spectra, photoabsorption spectra and photoelectron spectra of Ag₄M and Ag₄MCO clusters are forecasted and can be used to identify these clusters from experiment. Analysis of electronic properties indicates that the adsorption of CO on Ag₄M clusters changes the zero vibrational energy (ZPVE) and increases stability of the host clusters. Dopant atoms except for Zn improve the stability of silver cluster. The Ag₄Ni cluster shows high chemical activity and maximum adsorption energy for carbon monoxide. Magnetism calculations reveal that the magnetic moment of Ag₄M (M?=?Mn–Ni) cluster adsorbed by carbon monoxide is decreased by 2 μ_B. The change of magnetic moment makes it possible to be used as a nanomaterial for carbon monoxide detection. Simultaneously, it is found that the adsorption of CO on Ag₄Cu cluster is a physical adsorption.     

Experimental and numerical study of the propagation of focused wave groups in the nearshore zone

The propagation of focused wave groups in intermediate water depth and the shoaling zone is experimentally and numerically considered in this paper. The experiments are carried out in a two-dimensional wave flume and wave trains derived from Pierson-Moskowitz and JONSWAP spectrum are generated. The peak frequency does not change during the wave train propagation for Pierson-Moskowitz waves; however, a downshift of this peak is observed for JONSWAP waves. An energy partitioning is performed in order to track the spatial evolution of energy. Four energy regions are defined for each spectrum type. A nonlinear energy transfer between different spectral regions as the wave train propagates is demonstrated and quantified. Numerical simulations are conducted using a modified Boussinesq model for long waves in shallow waters of varying depth. Experimental results are in satisfactory agreement with numerical predictions, especially in the case of wave trains derived from JONSWAP spectrum.     

Comparison of two cold atmospheric pressure plasma jet configurations in argon

The present study compares the operation of two cold atmospheric plasma jet (CAPJ) configurations: needle-to-cylinder electrode configuration (CAPJ I) and single high-voltage cylinder electrode around the quartz tube (CAPJ II). The CAPJs were operated in argon flowing through a quartz capillary with 0.5-mm inner diameter into the ambient air, and the plasma was generated by sinusoidal kHz frequency AC power supplies. The main emphasis of the study was on the mechanism of the initiation of ionization waves for these two configurations. For both CAPJs, there appeared several ionization waves during one half-period of the applied voltage waveform, and the number of ionization waves increased at higher voltage amplitudes. However, we discovered marked differences in the initiation of the ionization waves for two different CAPJ configuration. The applied voltage controlled the initiation of consecutive ionization waves, which propagated from the grounded electrode towards the tube orifice in CAPJ I. In the case of CAPJ II, certain time had to pass for the initiation of a new ionization wave, and subsequent ionization waves within the same half-period started at the tube orifice. In addition to the differences in the initiation of the ionization waves, we observed that the CAPJ I was ignited and sustained at lower voltages, while CAPJ II produced a longer plasma jet. The observed advantages and deficiencies of investigated CAPJ configurations point out their potential in different applications.     

生长及耗散波色-爱因斯坦凝聚中的怪波

利用达布变换法(Darboux transformation),解析的研究了生长及耗散波色-爱因斯坦凝聚(BEC)中的怪波.通过降维和无量纲化,将描述BEC的Gross-Pitaevskii (GP)方程转化成一维无量纲非线性薛定谔方程.利用达布变换,得到了一维非线性薛定谔方程的怪波解析解.根据解析结果,数值模拟了生长及耗散BEC中怪波的性质.结果表明,BEC中出现了一种典型的双洞怪波,并且BEC生长会延缓怪波的消失,而BEC的耗散会加速怪波的消失.     

La掺杂和空位对ZnS磁性和光学性能影响的第一性原理研究

利用密度泛函理论框架下的平面波超软赝势法,通过第一性原理对La掺杂与Zn空位(V_(Zn))及La掺杂与S空位(V_S)共存的ZnS体系的电子结构、磁性机理、形成能及吸收光谱进行了研究.结果表明, La掺杂与空位(V_(Zn)或V_S)的空间位置最近时,掺杂体系的形成能最低,体系最稳定.另外,La掺杂与Zn空位共存时,体系具有磁性,且体系的净磁矩与La原子与Zn空位的相对位置有关;La掺杂与S空位共存时,掺杂体系无磁性,但此时体系的禁带宽度最窄且吸收光谱红移最显著.     

氨基酸官能团的太赫兹振动模式研究

对比于氨基酸的红外分析法,太赫兹波的电子能量更低,可实现无损检测。氨基酸分子内原子振动、分子间氢键的作用、以及晶体中晶格的低频振动均处于太赫兹波段,使其在太赫兹波段具有吸收峰,且不同的氨基酸分子太赫兹吸收峰不同,故可用氨基酸在太赫兹波段的这种“指纹特性”实现氨基酸类物质的定性分析。量子化学分析方法可以应用量子力学的基本原理和方法,研究稳定和不稳定分子的结构、性能及其之间的关系,还可以针对分子与分子间的相互作用、相互碰撞及相互反应等问题进行研究。通过量子化学计算方法计算氨基酸分子的太赫兹吸收谱,可以为氨基酸分子的太赫兹吸收峰匹配分子振动模式,对氨基酸定性分析有一定参考性与指向性,并为实验获取的样品太赫兹时域光谱提供理论支撑,在实验获得太赫兹吸收谱的基础上进行量子化学计算,还能为实验结果进行验证。首先利用太赫兹时域光谱技术获取了谷氨酰胺、苏氨酸、组氨酸的太赫兹吸收谱,分别构建这三种氨基酸样品在实物中以两性离子形式存在的单分子构型,利用量子化学计算方法在完成结构优化后进行太赫兹吸收谱模拟计算。计算结果表明三种氨基酸单分子的太赫兹吸收谱计算结果与实验获取的太赫兹吸收谱差异较大,但在高频段吸收峰峰位基本吻合。通过GaussView分别查看了这三种氨基酸分子在太赫兹段内的吸收峰对应频率处的振转情况,发现在高频段内三种氨基酸分子官能团均只发生转动而未见振动,并且转动模式基本一致。通过对氨基酸官能团的太赫兹吸收谱进行量子化学计算,将官能团在高频段内吸收峰对应频率处的振转模式与三种氨基酸分子在该段内吸收峰对应频率处的振转模式做了对比。研究表明,在氨基酸单分子构型下由量子化学方法计算所得的太赫兹吸收谱中,高频段内计算得出的模拟吸收峰与实验获取的太赫兹吸收峰基本吻合;振转模式分析发现,谷氨酰胺、苏氨酸、组氨酸在太赫兹高频段内的氨基酸官能团振转模式相同,三种氨基酸分子在高频段内的吸收峰主要来源于氨基酸官能团。因此,结合量子化学计算与太赫兹吸收谱可以实现氨基酸类物质的定性分析。     

暗怪波的相互作用

以耦合非线性薛定谔方程为理论模型,数值研究了两个一阶暗怪波在正常色散单模光纤中的相互作用.基于一阶暗怪波精确解,采用分步傅里叶数值模拟法,从间距、相位差和振幅系数比方面讨论相邻两个一阶暗怪波之间的相互作用.基于二阶暗怪波精确解,讨论了两个一阶暗怪波的非线性相互作用.研究结果表明:同相位情况下,间距参数T1为0、5、20时,相邻两个一阶暗怪波相互作用激发产生“扭结型”暗怪波.相比较于单个暗怪波发生能量的弥散,“扭结型”暗怪波分裂形成多个次暗怪波.反相位情况下,间距参数T1为2、7、12时,相邻两个一阶暗怪波相互作用也可以激发产生“扭结型”暗怪波.并且“扭结型”暗怪波初始激发的空间位置偏离原始单个暗怪波的位置5.振幅系数比越大,该空间位置越接近5.二阶暗怪波可以看作是两个一阶暗怪波的非线性叠加,复合型和三组分型二阶暗怪波与相邻两个一阶暗怪波的相互作用略有相似.     

Nd∶YVO4/Nd∶GdVO4双波长激光器的功率均衡实验研究

实验研究了Nd∶YVO4/Nd∶GdVO4双波长激光器在不同抽运功率条件下,通过调节热沉温度达到功率均衡时的输出特性.实验结果表明:对于Nd∶YVO4/Nd∶GdVO4双波长激光器,当提高抽运功率,需要重新降低热沉温度达到功率均衡输出,降温幅度与抽运功率增加之比为11.23℃/W.与此同时,随着抽运功率和热沉温度的变化,双波长激光器的中心波长会出现小幅度的漂移,左峰波长随抽运功率增加的蓝移速率为0.056 nm/W,右峰波长随抽运功率增加的蓝移速率为0.054 nm/W.实验还发现功率均衡条件下激光器的输出总功率随抽运功率的增加而增加,拟合斜效率为8.7%,当抽运功率为5.58 W时,输出最大总功率达到115.7 mW.