相对论小分量波函数对原子光电离截面的影响

利用相对论平均自洽场理论,　研究了相对论波函数的小分量对原子光电离截面的影响。原子核尺寸效应将使波函数小分量对原子光电离截面的影响减弱。由于波函数沿径向空间被压缩,　电子离核的平均半径较小,　波函数小分量对高离化态离子光电离截面的影响比对一般原子要强得多。波函数小分量反映了相对论效应的基本特征,　从而也定性地说明了光电离过程中相对论效应的强弱。The effects of relativistic small radial component on atomic photoionization cross sections have been studied within relativistic average self consistent field theory. Relativistic effects are relatively unimportant for low photon energy, along with a review of high energy photoionization the relativistic effects are quite important. The effects of relativistic small radial component on photoionization process should show breakdown when the nuclear finite size effects is taken into account. The compression of wavefunction into the space near nucleus is so strong in highly charged ions that the electronic radius greatly decreases, and the effects of relativistic small radial component on photoionization cross sections turn to stronger than ordinary atoms. Since relativistic effects are extremely sensitive to the behavior of small radial component, the results are in good agreement with relativistic effects on photoionization cross section.     

求解非线性传输线方程的简便方法

应用sine-cosine方法构造了非线性传输线方程的周期波解和孤波解.结果表明,sine-cosine方法是一种简便、有效的方法,并且可以用于求解其他非线性方程.     

原子实对离子n壳层辐射复合截面的影响

基于Dirac-Slater相对论平均自洽场理论和类氢模型,研究了自由电子被辐射复合到裸核和类裸核离子的n壳层时RR截面随自由电子能量的变化,以及原子实对这种变化的影响;给出了两种理论模型下RR截面曲线变化的差异,并对这种差异做了较详细的理论说明.     

Isothermal bulk modulus and its first pressure derivative of NaCl at high pressure and high temperature

The isothermal bulk modulus and its first pressure derivative of NaCl are investigated using the classical molecular dynamics method and the quasi-harmonic Debye model.To ensure faithful molecular dynamics simulations,two types of potentials,the shell-model(SM) potential and the two-body rigid-ion Born-Mayer-Huggins-Fumi-Tosi(BMHFT) potential,are fully tested.Compared with the SM potential based simulation,the molecular dynamics simulation with the BMHFT potential is very successful in reproducing accurately the measured bulk modulus of NaCl.Particular attention is paid to the prediction of the isothermal bulk modulus and its first pressure derivative using the reliable potential and to the comparison of the SM and the BMHFT potentials based molecular dynamics simulations with the quasi-harmonic Debye model.The properties of NaCl in the pressure range of 0-30 GPa at temperatures up to the melting temperature of 1050 K are investigated.     

下地幔条件下钙钛矿结构MgSiO3熔化行为的研究

利用分子动力学方法结合有效的对势,模拟了下地幔条件下钙钛矿结构MgSiO3的熔化曲线．研究表明,分子动力学模拟结果精确地再现了广泛压强范围内钙钛矿结构MgSiO3的状态方程,并且熔化曲线与最新的实验结果也符合的很好．在压强上升到下地幔压强范围内,压强低于60 GPa时的钙钛矿结构MgSiO3熔化曲线比较陡,接着变得平缓．在核幔边界压强135 GPa时,钙钛矿结构MgSiO3的熔化温度是6500 K,明显低于Zerr和Boehler实验结果的外推结果．     

量子数n和l对束缚电子径向波函数的影响

利用Hartree-Fork平均自洽场理论,研究了主量子数n和角量子数l对束缚电子波函数影响的主要特征.原子实通常是致密、紧凑的,当n和l较大时价电子的行为将与相应的氢原子电子相似;在靠近核的原子实区域,原子实的影响使价电子径向波函数节点的位置几乎重合.在近核区域离心势可对电子产生很大影响:小l电子只能轻微地贯穿到原子实的较深区域,对大l电子离心势将阻止其深入到离核很近的原子实内;离化度较高时离心势的作用相对减弱,电子深入到原子实内的可能性较大.     

Effect of pressure on the thermal expansion of MgO up to 200~GPa

Constant temperature and pressure molecular dynamics (MD) simulations are performed to investigate the thermal expansivity of MgO at high pressure, by using effective pair-wise potentials which consist of Coulomb, dispersion, and repulsion interactions that include polarization effects through the shell model (SM). In order to take into account non-central forces in crystals, the breathing shell model (BSM) is also introduced into the MD simulation. We present a comparison between the volume thermal expansion coefficient α dependences of pressure P at 300 and 2000~K that are obtained from the SM and BSM potentials and those derived from other experimental and theoretical methods in the case of MgO. Compared with the results obtained by using the SM potentials, the MD results obtained by using BSM potentials are more compressible. In an extended pressure and temperature range, the α value is also predicted. The properties of MgO in a pressure range of 0--200~GPa at temperatures up to 3500~K are summarized.     

非线性电报方程的简洁解法

应用tanh-coth方法对非线性电报方程进行了求解.得到了孤波解、三角函数周期波解等一些不同形式的行波解.结果表明,tanh-coth方法是一种简便、有效的方法,并且可用于求解其他非线性方程.     

非线性压电杆波动方程的几类新精确解

应用修正tanh-coth方法求解了非线性压电杆波动方程,得到了包括孤波解在内的双曲函数解和三角函数周期波解等一些不同形式的新精确解,并给出了一些具有物理意义的解的图像。从求解过程可以看出,在求解非线性数学物理偏微分方程的问题方面,修正tanh-coth方法是一种简便、有效的方法。     

新型二维压电声子晶体板带隙可调性研究

设计了一种由涂有硬质材料涂层的柱状压电散射体周期性连接在四个环氧树脂薄板上构成的具有大带宽的新型二维压电声子晶体板,并利用有限元方法计算了该声子晶体板的能带结构、传输损失谱和位移矢量场.研究表明：与二组元材料构成的传统声子晶体板相比,新设计的声子晶体板的第一完全带隙频率更低,并且带宽扩大了5倍;通过在压电体表面上施加不同的电边界条件,可以实现多条完全带隙的主动调控;压电效应对能带结构有很大的影响,并且有利于完全带隙的扩大与形成.基于带隙的可调谐性,分析了可切换路径的压电声子晶体板波导,结果表明可以通过改变电边界条件来限制弹性波能量流.