平行板间方势阱偶极流体的结构性质研究

在密度泛函理论(DFT)框架下, 应用改进的基本度量理论(MFMT)表达硬球作用对自由能泛函的贡献, 根据统计力学理论结合加权密度近似(WDA)表达偶极作用对自由能泛函的贡献,得到了方势阱偶极流体在平行板间的密度分布表达式, 计算了偶极流体在两平行板间的密度分布, 并探讨了方势阱深度和宽度对体系密度分布的影响. 此外, 通过体系密度分布, 进一步分析了方势阱宽度和深度以及板间尺度与溶剂化力的关系.     

平行板间方势阱偶极流体的结构性质研究

在密度泛函理论(DFT)框架下, 应用改进的基本度量理论(MFMT)表达硬球作用对自由能泛函的贡献, 根据统计力学理论结合加权密度近似(WDA)表达偶极作用对自由能泛函的贡献,得到了方势阱偶极流体在平行板间的密度分布表达式, 计算了偶极流体在两平行板间的密度分布, 并探讨了方势阱深度和宽度对体系密度分布的影响. 此外, 通过体系密度分布, 进一步分析了方势阱宽度和深度以及板间尺度与溶剂化力的关系.     

Collective modes of one-dimensional lennard-jones systems

The density fluctuations of one-dimensional Lennard-Jones systems are investigated by molecular dynamics simulation. The full Lennard-Jones potential is compared to the repulsive Lennard-Jones potential. It is found that the behavior of the density fluctuations at small wave vectors is determined by the repulsive portion of the potential. The variation of the fluctuations with density is explained. It is shown that these systems do not display hydrodynamics.     

The Explicit Density Functional and Its Connection with Entropy Maximization

The intrinsic Helmholtz free energy, commonly used as a basis for density functional theories, is here given explicitly as a cluster diagram expansion with density field points. Also given are explicit variational procedures for determining the chemical potential for a given density, the pair potential for a given pair correlation function, and the pair correlation function for a given pair potential. The physical meaning of the density functional is established within the context of a new derivation of statistical mechanics based on entropy that supplies a variational principle for equilibrium by generalizing the thermodynamic potential to nonequlibrium states. This shows that the conventional density functional determines not only the equilibrium density, but also the probability of fluctuations about that density.     

一个非晶InGaZnO薄膜晶体管线性区陷阱态的提取方法

非晶InGaZnO(a-IGZO)薄膜在制备过程中形成的缺陷和弱键以陷阱态的形式非均匀分布在a-IGZO的带隙中, 这些陷阱态会俘获栅压诱导的电荷, 影响a-IGZO薄膜晶体管线性区迁移率、沟道电子浓度等, 进而影响线性区的电学性能. 本文基于线性区沟道迁移率与沟道内的自由电荷与总电荷的比值成正比, 分离出自由电荷以及陷阱态电荷. 由转移特性和电容电压特性得到自由电荷以及陷阱态电荷对表面势的微分, 分离出自由电子浓度和陷阱态浓度. 通过对沟道层与栅绝缘层界面运用泊松方程以及高斯定理, 考虑了沟道表面势与栅压的非均匀性关系, 得出自由电子浓度以及陷阱态浓度与表面势的关系, 最后通过陷阱态浓度与表面势求导得到线性区对应的态密度.     

Synthesis of highly ordered nanopores on alumina by two-step anodization process

Highly ordered anodic alumina was produced, on RF sputtered aluminium on a conductive glass substrate, by two step anodizing process in 0.4 M sulphuric acid at constant cell potentials of between 5 and 25 V and at a constant current density of 20 mA cm⁻². The temperature was kept constant at 15 °C during both anodization processes. The effects of the anodizing potential, current density, and time on the pore diameters were established. Longer anodization periods result in wider irregular pores with reduced porosity for both constant potential and constant current density anodization processes. The current density increases with increasing constant anodizing potential and generally remains constant with time after a sharp rise. Potential drop during constant current density anodization behaves in a similar manner. We confirm that sulphuric acid has a self-ordering potential of 25 V above which burning occurs.     

Extreme values of elastic strain and energy in sine-Gordon multi-kink collisions

In our recent study the maximal values of kinetic and potential energy densities that can be achieved in the collisions of N slow kinks in the sine-Gordon model were calculated analytically (for N = 1, 2, and 3) and numerically (for 4 ≤ N ≤ 7). However, for many physical applications it is important to know not only the total potential energy density but also its two components (the on-site potential energy density and the elastic strain energy density) as well as the extreme values of the elastic strain, tensile (positive) and compressive (negative). In the present study we give (i) the two components of the potential energy density and (ii) the extreme values of elastic strain. Our results suggest that in multi-soliton collisions the main contribution to the potential energy density comes from the elastic strain, but not from the on-site potential. It is also found that tensile strain is usually larger than compressive strain in the core of multi-soliton collision.     

Prediction of the derivative discontinuity in density functional theory from an electrostatic description of the exchange and correlation potential

We propose an approach to approximate the exchange and correlation (XC) term in density functional theory. The XC potential is considered as an electrostatic potential, generated by a fictitious XC density, which is in turn a functional of the electronic density. We apply the approach to develop a correction scheme that fixes the asymptotic behavior of any approximated XC potential for finite systems. Additionally, the correction procedure gives the value of the XC derivative discontinuity; therefore, it can directly predict the fundamental gap as a ground-state property.     

Mean distribution of single-particle levels in thin-skinned potential wells and the macroscopic level density parameters of nuclei

A general leptodermous expansion for the density of single-particle levels in thin-skinned potential wells is derived and is used to study the finite size corrections to the macroscopic level density parameters of nuclei. With droplet model values for the potential parameters, the calculated level density parameters for nuclei along the β-stability line show systematic deviations from the experimental estimates. Possible reasons for these deviations are also discussed.     

The Spectral Density of the Scattering Matrix for High Energies

We determine the density of eigenvalues of the scattering matrix of the Schr?dinger operator with a short range potential in the high energy asymptotic regime. We give an explicit formula for this density in terms of the X-ray transform of the potential.     

非对称核物质中同位旋对称势的动量和密度依赖性

在Brueckner-Hartree-Fock理论框架内, 研究了同位旋非对称核物质中质子和中子单粒子势的动量相关性及其随同位旋非对称度的变化, 在此基础上计算了同位旋对称势, 并讨论了三体核力的影响. 结果表明同位旋对称势对于同位旋非对称度的依赖性很弱, 但对于动量和密度均有较强的依赖性. 当密度固定时, 同位旋对称势随动量增加而减小. 尽管三体核力对于质子和中子单粒子势的动量相关性有较大影响, 但对同位旋对称势的影响很小. 还与目前重离子碰撞输运理论模型中所使用的各种参数化的唯象对称势进行了比较.     

The effective potential originating from swampland and the non-trivial Brans-Dicke coupling

The effective vacuum energy density contributed by the non-trivial contortion distribution and the bare vacuum energy density can be viewed as the energy density of the auxiliary quintessence field potential. We find that the negative bare vacuum energy density from string landscape leads to a monotonically decreasing quintessence potential while the positive one from swampland leads to the metastable or stable de Sitter-like potential. Moreover, the non-trivial Brans-Dicke like coupling between the quintessence field and gravitation field is necessary in the latter case.     

磁通量对二维谐振子的量子能级密度的影响

利用周期轨道理论,我们计算了在不同情况下,一个粒子在二维谐振子势中存在和不存在磁通量时的量子能级密度.重点讨论了磁通量对量子能级密度的影响.计算结果表明:当二维谐振子势的频率比值是有理数时,量子能级是分立的,能级密度中的每一条峰正好对应一个量子能级.然而,当频率比是无理数时,能级密度发生振荡,当加上磁通量后,振荡减小.这可以看作是Aharonov-Bohm效应的结果.     

Inclusion of the Δ resonance in the optical potential between two nuclei and its application to medium energy12C-12C scattering

An energy dependent complex optical potential between two nuclei is calculated from the potential energy density for two colliding nuclear matters generated by solving the Bethe-Goldstone equation in whichNΔ and ΔΔ channels are explicitly coupled to theNN channel. By adding the contributions from the third and fourth order ring diagrams and the relativistic correction to the calculated potential energy density, the saturation property of a nuclear matter is reasonably well reproduced. This is used together with the kinetic energy density to calculate the optical potential for the¹²C+¹²C system in the energy density formalism with the local density approximation. The surface correction term and the symmetry energy term in the energy density functional are determined to reproduce the observed binding energy and the rms radius of¹²C. Using this potential, the differential cross sections for elastic¹²C-¹²C scattering atE _lab=1440 and 2400 MeV are calculated and compared with recent experimental data.     

极光带下层区电双层及密度空穴

 为了得到极光带下层区电双层及密度空穴的形成和演化过程,分析了在静态极限下,强湍动等离子中低频电势、高频调制场及密度扰动之间的非线性耦合方程,并对其进行了数值计算。结果表明,在极光带下层区,坍塌的高频场导致了电双层及密度空穴的形成。所得的电双层为双双层,是一种非线性的实体,即腔子,其电势峰值范围为14～40 V,厚度为100～200 m,几十个Debye尺度;空穴的最大密度扰动率达到80%以上,这与FAST卫星观测结果相一致。     

One-dimensional classical fluid with nearest-neighbor interaction in arbitrary external field

We consider the equilibrium statistical mechanics of a classical one-dimensional simple fluid, with nearest-neighbor interactions, and in an arbitrary external potential. The external potential is eliminated to yield relations between the truncated partition functions and the one-body density. These relations are solved for pure cores and for sticky cores, resulting in each case in both an explicit potential density relation and grand potential density functional. Both models maintain finite-range direct correlations and have grand potentials expressible in terms of simple linear density transforms.Rearch supported in part by NSF grant No. CHE-80011285, DOE contract No. DE-AC02-76ER03077, and CNPq 40.0438/79 (Brasil).     

Microscopic view of charge injection in an organic semiconductor

We have measured the chemical potential and capacitance in a disordered organic semiconductor by electric force microscopy, following the electric field and interfacial charge density microscopically as the semiconductor undergoes a transition from Ohmic to space-charge limited conduction. Electric field and charge density at the metal-organic interface are inferred from the chemical potential and current. The charge density at this interface increases with electric field much faster than is predicted by the standard diffusion-limited thermionic emission theories.     

Microscopic quadrupole and hexadecapole moments of rare earth nuclei

The theoretical calculations of multipole moments of even-even rare earth nuclei are presented. The potential energy surface is evaluated by the shell correction method. The condition ensuring the equality of the density distribution of the macroscopic liquid droplet part of the potential energy and the density generated by the single particle potential is added. A single particle Nilsson potential is used. New, less stiff potential surfaces versusε ₄ are obtained while the multipole moments calculated at the equilibrium deformations agree well with experimental data.     

Potential profile near the virtual cathode in presence of charged dust

In this work, concept of virtual cathode and its existence in dusty plasma has been studied by theoretical and numerical analysis. Using basic equations of charge dust, ions, and electrons, the non‐monotonic behaviour of the potential in presence of charged dust has been calculated and plotted as a function of dust density. It has been found that there is a change in potential between cathode and sheath potential and subsequently changes the threshold wall temperature as compared to that of without dust conditions. The threshold wall temperature has been increased due to the ability of micro‐particles acquiring electron charge and hence, reducing potential at the wall. Further, for different values of α (depends on dust density); threshold temperature remained the same for observed virtual cathode. Hence, behaviour of potential has been plotted as a function of α with increasing wall temperatures for two dust charge values (1 and 1,000). Considering no dust charge, it has been observed that, at lower dust density, double layer like structure is formed near the emissive wall. But this double layer structure gets diminishes with increasing dust density. Hence, below a threshold dust density, virtual cathode near to the emissive wall is not possible. While for Z_d = 1,000, the formation of virtual cathode appeared even at very small dust density. However, irrespective of variation of potential difference near the wall and existence of virtual cathode at different emission regime the threshold wall temperature remains same. Effect of dust potential dependency on threshold wall temperature has also been discussed in this study.     

The effect of a periodic absorptive strip arrangement on an interior sound field in a room

In this paper we study the effect of periodically arranged sound absorptive strips on the mean acoustic potential energy density distribution of a room. The strips are assumed to be attached on the room's surface of interest. In order to determine their effect, the mean acoustic potential energy density variation is evaluated as the function of a ratio of the strip's arrangement period to wavelength. The evaluation demonstrates that the mean acoustic potential energy density tends to converge. In addition, a comparison with a case in which absorptive materials completely cover the selected absorptive plane shows that a periodic arrangement that uses only half of the absorptive material can be more efficient than a total covering, unless the frequency of interest does not coincide with the room's resonant frequencies. Consequently, the results prove that the ratio of the arrangement period to the wavelength plays an important role in the effectiveness of a periodic absorptive strip arrangement to minimize a room's mean acoustic potential energy density.