Heavy-ion fusion cross-section calculations in classical microscopic equations of motion approach

Fusion cross-sections for¹⁶O +¹⁶O reaction earlier calculated in classical microscopic equations of motion approach, with Lennard-Jones form ofNN interaction potential are overestimated compared to the experimental data at lower energies. This large deviation was attributed to possible break down of classical approximations at lower energies. The aim of this paper is to show that this discrepancy was rather due to certain assumptions made in the specification of initial conditions; in particular due to neglect of Coulomb interaction between the colliding ions at far off distances. Use of Lennard-Jones potential is also critically examined.     

Screening effect of impurities in metals: a possible explanation of the process of cold nuclear fusion

Summary The screening length of the deuterium ion by surrounding electrons in a palladium metal lattice, as estimated using two approaches—viz. the Thomas-Fermi screening theory and the Debye screening theory for plasmas in metal—is found to be less than the interatomic separation of ordinary hydrogen molecules. This has important implications for the possibility of cold nuclear fusion at room temperature, since slight fluctuations in equilibrium conditions may drive the deuterons to fuse together. The relative magnitudes of screening length for the cold nuclear fusion regime and classical hot nuclear regimes (inertial and magnetic confinement) reveal that in the former a comparatively smaller amount of energy is needed to overcome the repulsive Coulomb barrier between two deuterium ions.     

Remarks on global existence for the supercritical nonlinear Schrödinger equation with a harmonic potential

This paper is concerned with the nonlinear Schrödinger equation with a harmonic potential which describes the attractive Bose–Einstein condensate under the magnetic trap. By combining the best constant of Gagliardo–Nirenberg's inequality with the characteristic of this equation, we derive out a global existence condition for the supercritical equation which coincides with the critical case.     

等离子体湍流能量传输的尺度相关性

对于空间环境中近乎无碰撞的等离子体,可采用Vlasov方程进行理论描述,基于Vlasov方程,讨论了等离子体湍流能量传输和耗散的过程:由亚格子应力引起的尺度间的能量传输,电场做功,压强张量做功（压强张量与速度梯度张量的相互作用）.通过混合Vlasov-Maxwell（HVM）数值模拟,进一步研究了能量传输通道之间的联系与区别.不同能量传输通道尽管在不同尺度起主要作用,但其空间的分布非常相似,即各能量传输通道之间存在一定的空间相关.结合近年数值模拟和卫星观测的结果,可以大致概括等离子体湍流从磁流体动力学（magnetohydrodynamic,MHD）尺度到动理学尺度的能量传输过程.      

Full counting statistics of phonon transport in disordered systems

The coherent potential approximation (CPA) within full counting statistics (FCS) formalism is shown to be a suitable method to investigate average electric conductance, shot noise as well as higher order cumulants in disordered systems. We develop a similar FCS-CPA formalism for phonon transport through disordered systems. As a byproduct, we derive relations among coefficients of different phonon current cumulants. We apply the FCS-CPA method to investigate phonon transport properties of graphene systems in the presence of disorders. For binary disorders as well as Anderson disorders, we calculate up to the 8-th phonon transmission moments and demonstrate that the numerical results of the FCS-CPA method agree very well with that of the brute force method. The benchmark shows that the FCS-CPA method achieves 20 times more speedup ratio. Collective features of phonon current cumulants are also revealed.     

N-乙基吡咯S1态超快动力学：飞秒时间分辨光电子成像研究

N-乙基吡咯是吡咯分子的一个乙基取代衍生物,它的激发态衰变动力学目前为止很少被研究. 本文利用飞秒时间分辨光电子成像的实验方法研究N-乙基吡咯分子S₁态的衰变动力学. 实验采用241.9和237.7 nm的泵浦激发波长. 在241.9 nm激发下,得到5.0±0.7 ps,66.4±15.6 ps和1.3±0.1 ns三个寿命常数. 在237.7 nm激发下,得到2.1±0.1 ps和13.1±1.2 ps两个寿命常数. 所有寿命常数都归属为S₁态的振动态. 本文并对不同S₁振动态的弛豫机理进行了讨论.     

Ab initio方法研究~(40)Ca~(35)Cl分子的自旋轨道耦合效应和跃迁性质

本文研究了~(40)Ca~(35)Cl分子低态的自旋轨道耦合分裂以及获得更精确的光谱常数和更高的激发态.以从头算理论为基础,使用多参考组态相互作用方法获得了该分子的势能曲线和自旋轨道分裂,之后求解径向一维薛定谔方程获得光谱常数.得到了~(40)Ca~(35)Cl分子7个Λ-S低电子态的势能曲线和永久偶极矩,以及A~2Π→~2Σ~+,1~2Δ和C~2Π→~2Σ~+,1~2Δ跃迁的跃迁偶极矩,得到的光谱常数(不管是考虑了自旋轨道耦合(SOC)还是没有考虑SOC)与实验值非常符合,且要好于之前的理论计算结果 .值得注意的是,目前的计算还首次得到了C~2Π→~2Σ+,1~2Δ跃迁的跃迁性质,为之后实验观察~(40)Ca~(35)Cl分子的高激发态光谱和跃迁性质提供有益的理论参考.     

Configuration interaction study on low-lying states of AlCl molecule

High-level ab initio calculations of the Λ–S states for aluminum monoiodide(Al Cl) molecule are performed by utilizing the explicitly correlated multireference configuration interaction(MRCI-F12) method. The Davidson correction and scalar relativistic correction are investigated in the calculations. Based on the calculation by the MRCI-F12 method, the spin–orbit coupling(SOC) effect is investigated with the state-interacting technique. The adiabatic potential energy curves(PECs) of the 13 Λ–S states and 24 Ω states are calculated. The spectroscopic constants of bound states are determined,which are in accordance with the results of the available experimental and theoretical studies. Finally, the transition properties of 0~+(2)–X0~+, 1(1)–X0~+, and 1(2)–X0~+ transitions are predicted, including the transition dipole moments(TDMs),Franck–Condon factors(FCFs), and the spontaneous radiative lifetimes.     

Anisotropic exciton Stark shift in hemispherical quantum dots

The exciton Stark shift and polarization in hemispherical quantum dots(HQDs) each as a function of strength and orientation of applied electric field are theoretically investigated by an exact diagonalization method. A highly anisotropic Stark redshift of exciton energy is found. As the electric field is rotated from Voigt to Faraday geometry, the redshift of exciton energy monotonically decreases. This is because the asymmetric geometric shape of the hemispherical quantum dot restrains the displacement of the wave function to the higher orbital state in response to electric field along Faraday geometry. A redshift of hole energy is found all the time while a transition of electron energy from this redshift to a blueshift is found as the field is rotated from Voigt to Faraday geometry. Taking advantage of the diminishing of Stark effect along Faraday geometry, the hemispherical shapes can be used to improve significantly the radiative recombination efficiency of the polar optoelectronic devices if the strong internal polarized electric field is along Faraday geometry.