块体非晶合金的黏度与玻璃形成能力的关系

基于经典结晶理论讨论了非晶合金的晶化动力学因素和晶化热力学因素对玻璃形成能力（GFA）的影响.分析表明,合金的等温转变（TTT）曲线“鼻尖”温度T_n对应的黏度与晶化阻力因子成正比;重新加热时晶化开始温度T_x对应的黏度与晶化驱动力因子成反比.由此得到了新的GFA参数ω₀=（T_g-T₀）/（T_x-T₀）-（T_g-T₀）/（T_n-T₀）,其中T_g为玻璃转变温度,T₀为理想玻璃转变温度.统计结果显示,ω₀与临界冷却速率具有较高的相关性,R²高达09626.进一步分析表明：新提出的ω₀参数可以合理地解释过冷熔体的黏度、脆性、液相稳定性、热稳定性以及T_rg、ΔT_x、γ、γ_m、ΔT_rg、α、β、δ和φ等参数与GFA的关系. 关键词： 块体非晶合金 黏度 脆性 玻璃形成能力     

Correlation of fragility with mechanical moduli in double-well potential for glass-forming liquid

The shoving model and the Vogel-Fulcher relation are employed to derive correlation of the fragility with the mechanical moduli for glass-forming simple liquids. The result shows that a liquid with smaller fragility will have larger ratio of K_∞/G_∞ in dilute liquid system. Based on radial distribution function with the Lennard-Jones potential modified by the Gaussian potential with a second minimum, fragility of the supercooled simple liquid is derived from the correlation between viscosity and shear modulus via configurational entropy. The results demonstrate that the fragility is determined by two parts: thermodynamic components and mechanical moduli. For a weak Gaussian potential liquid, the fragility is proportional to the T_g, while for a strong one, the fragility is inversely proportional to the T_g, and the Gaussian potential will increase fragility.     

The relationship between viscosity and glass forming ability of Al-(Ni)-Yb alloy systems

The dynamic viscosity of Al-Yb and Al-Ni-Yb superheated melts was measured using a torsional oscillation viscometer. The results show that the temperature dependence of viscosity fits the Arrhenius law well and the fitting factors are calculated. The amorphous ribbons of these alloys were produced by the melt spinning technique and the thermal properties were characterized by using a differential scanning calorimetry (DSC). E (the activation energy for viscous flow), which reflects the change rate of viscosity, has a good negative relation with the GFA in both Al-Yb and Al-Ni-Yb systems. However, there is no direct relation between liquidus viscosity (ηL) and GFA. The superheated fragility M can predict GFA in Al-Yb or Al-Ni-Yb alloy system.     

Relations between Varshni and Morse potential energy parameters

A set of relationships between the Morse and Varshni potential functions for describing covalent bondstretching energy has been developed by imposing equal force constant and equal energy integral. In view of the extensive adoption of Morse function in molecular force fields, this paper suggests two sets of parameter conversions from Varshni to Morse. The parameter conversion based on equal force constant is applicable for small change in bond length, while the parameter conversion based on equal energy integral is more applicable for significant bond-stretching. Plotted results reveal that the Varshni potential function is more suitable for describing hard bonds rather than soft bonds.      

Correlation between liquid structure and glass forming ability in glassy Ag-based binary alloys

The atomic structures of liquid Ag-based binary alloys have been investigated in the solidification process by means of X-ray diffraction. The results of liquid structure show that there is a break point in the mean nearest neighbor distance r1 and the coordination number Nmin for glass-forming liquid, while the correlation radius rc and the coordination number Nmin display a monotone variational trend above the break point. It means glass-forming liquids have a steady changing in structure above liquidus a...     

相互作用能、势能以及极化状态改变作功

指出在一般教学参考书中给出的静电场互作用能公式，仅仅是电势能公式，两个带电物体间的相互作用能，除了势能以外，还应包括由于相互极化导致物体极化导致物体状态改变所作的功和外电源提供的能量，本导出了两个带电物体间相互作用能的普遍公式。     

The true potential energy curves for different states of SiO and SiS molecules

The true potential energy curves forX ¹ Σ ⁺, a³ π _r,A ¹ π,e ³ Σ ⁻,E ¹ Σ ⁺,c ³ π _i states of astrophysically important molecule SiO, whose spectra were observed in the sunspots, have been constructed using the method of Lakshman and Rao. Dissociation energy and ionization potential have been estimated as 65,350 cm⁻¹ and 92,854 cm⁻¹ respectively and found to be in good agreement with the values cited in literature. The true potential energy curves forX ¹ Σ ⁺,D ¹ π andE ¹ Σ ⁺ states of SiS molecule have been constructed by the same method and its dissociation energy in the ground state has been estimated using Hulburt-Hirschfelder potential function as 54,765 cm⁻¹ in good agreement with 53,250.9 cm⁻¹ given by Herzberg.     

Pu_2分子的结构与势能函数

用相对论有效原子实势 (RECP)和密度泛函 (B3LYP)方法对Pu2 分子的结构进行了优化 ,对较高多重性优化得到两个平衡结构 ,并用Murrell Sorbie函数导出了基态两种结构的势能函数和光谱数据。     

PuNO分子结构与势能函数

本文运用密度泛函理论的B3LYP方法, 对钚原子应用LANL2DZ收缩价基函数, 氮、氧原子采用AUG-cc-pVTZ基函数, 分别对PuN, PuO, NO和PuNO体系进行了结构优化, 得到PuNO分子最稳构型为C_∞v (Pu-N-O), 电子态为⁶Σ^- (基态), 平衡核间距R_ON=0.12257 nm, R_NPu=0.22951 nm, 离解能D_e=8.10537 eV. 同时优化得到PuNO 分子存在两种亚稳态平衡构型分别为C_∞v (Pu-O-N), ⁶Σ^- (电子态)和C_s (O-Pu-N), A" (电子态), 以及分子体系相应的力学常数等. 拟合出PuN, PuO 和NO 分子的Murrell-Sorbie势能函数, 并使用多体项展式理论得到了PuNO分子的分析势能函数, 其等值势能图准确再现了PuNO分子最稳态构型及两个亚稳态构型的离解能和结构特性, 由此讨论了该分子体系的势能面静态特征.     

Molecular structure and analytical potential energy function of SeCO

The density functional method(B3P86/6-311G) is used for calculating the possible structures of SeC, SeO, and SeCO molecules. The result shows that the ground state of the SeC molecule is1Σ, the equilibrium nuclear distance is RSeC= 0.1699 nm, and the dissociation energy is De = 8.7246 eV. The ground state of the SeO molecule is3Σ, with equilibrium nuclear distance RSeO= 0.1707 nm and dissociation energy De = 7.0917 eV. There are two structures for the ground state of the SeCO molecule: Se=C=O and Se=O=C. The linear Se=C=O is1Σ. Its equilibrium nuclear distances and dissociation energy are RSeC= 0.1715 nm, RCO= 0.1176 nm and 18.8492 eV, respectively. The other structure Se=O=C is1Σ. Its equilibrium nuclear distances and dissociation energy are RCO= 0.1168 nm, RSeO= 0.1963 nm and 15.5275 eV,respectively. The possible dissociative limit of the SeCO molecule is analyzed. The potential energy function for the SeCO molecule has been obtained from the many-body expansion theory. The contour of the potential energy curve describes the structure characters of the SeCO molecule. Furthermore, contours of the molecular stretching vibration based on this potential energy function are discussed.     

GeHn±(n=0,1,2)的势能函数和光谱常数研究

用密度泛函B3lyp/6-311++g(d,p)方法对 分子离子进行理论研究。结果表明：GeH,GeH+,GeH-1均能稳定存在,GeH+2和GeH-2有亚稳定态存在,其基态电子态分别是: 2Π(GeH),1Σ(GeH+),3Σ(GeH-),2Σ(GeH+2)和2Π(GeH-2),GeH+2和GeH-2的势能函数呈明显的‘火山态’型,导出了相应的分子离子的解析势能函数、光谱数据和力常数,比较了四参数、八参数Murrell-Sorbie势和Zhu-Wang势对不稳定分子势能函数的拟合情况,指出了用八参数Murrell-Sorbie势对‘火山态’型势能函数的拟合也是合适的;同时讨论了电荷对势能函数和能级的影响。     

关于分析力学中势能的一个注记

指出了理论力学教材中分析力学部分关于势能与力的关系的一点不足之处,具体讨论了势能的表示式.     

PdCO分子结构与势能函数

用密度泛函理论的B3LYP方法,对钯原子采用LANL2DZ收缩价基函数,碳原子和氧原子采用AUG-cc-pVTZ基组,对PdC,PdO和PdCO体系的结构进行优化,计算表明：PdC分子基态为¹Σ⁺态,键长为R_e=0.17285nm,离解能为4.919eV.PdO分子基态的平衡核间距为0.18546nm,其电子态为³Π,离解能为2.455eV,并拟合得到Murrell-Sorbie势能函数;PdCO分子有两 关键词： PdCO 分子结构 势能函数     

大气中HCO~+与COH~+ 分子体系的分析势能函数

在从头算的基础上,对HCO+和COH+的全势能表面用多体项展式方法进行优化,确定了分析势能函数,并且正确地再现了HCO+和COH+的结构与能量,预测了HCO+与COH+异构化的角形鞍点     

Mass and thermal transport in liquid Cu-Ag alloys

In this paper, the diffusion, thermodynamic and thermotransport properties in Cu–Ag liquid alloys are extensively investigated with molecular dynamics over a wide composition and temperature range. The simulations are performed with the most reliable EAM potential. The Green-Kubo formalism is employed for calculating transport properties. It is found that the reduced heat of transport in Cu–Ag is very small (about 0.10?eV in absolute value) and almost temperature independent. Further it is found that the interdiffusion coefficient together with both self-diffusion coefficients are almost composition independent. In Cu–Ag, the thermodynamic factor is found to be less than unity whereas the Manning factor is greater than unity (with significant composition and temperature dependence) and their product is very close to 1.     

并五苯同质异相体中分子间势能与能带计算

采用Born-Mayer-Haggins对势模型，分析了并五苯分子间势能及其相互作用. 用紧束缚模型计算了两种并五苯同质异相体结构的能带宽度. 计算带宽随温度升高减小8%—14%. 关键词： 并五苯 同质异相体 分子间势能 能带计算     

Two-dimensional potential energy function for internal rotation in 1,2-dihydroxybenzenes

We have obtained an analytical expression for the two-dimensional potential energy function for internal rotation in 1,2-dihydroxybenzenes, allowing us to use perturbation theory methods to calculate and interpret the torsional spectra of these compounds. __________ Translated from Zhurnal Prikladnoi Spektroskopii, Vol. 73, No. 1, pp. 133–136, January–February, 2006.     

Effective interactions between concentration fluctuations and charge transfer in chemically ordering liquid alloys

Summary The correlations between long-wavelength fluctuations of concentration in a liquid binary alloy are determined by a balance between an elastic-strain free energy and an Ornstein-Zernike effective interaction. The latter is extracted from thermodynamic data in the case of the Li−Pb system, which is well known to chemically order with stoichiometric composition corresponding to Li₄Pb. Strong attractive interactions between concentration fluctuations near the composition of chemical ordering originate from electronic charge transfer, which is estimated from the electron-ion partial structure factors as functions of composition in the liquid alloy. In honour of Prof. Fausto Fumi on the occasion of his retirement from teaching.     

Na2H的基态结构与势能函数

采用二次组态相关(QCISD)方法对NaH分子进行理论计算,得到它的几何结构、光谱性质,并拟合出它的Murrell-Sorbie势能函数.应用密度泛函(B3LYP)方法,在6-311G(3df,3pd)基组水平上对Na2H分子的基态结构进行优化,并用同样的基组对该分子进行了进一步的频率计算.结果发现Na2H分子的基态稳态结构为C2v构型,采用多体项展式理论导出了它的解析势能函数,其等值势能图准确再现了Na2H分子的结构特征和离解能.并报导了该分子对称伸缩振动等值势能图中存在的两个对称鞍点,对应于反应NaH Na→Na2H,活化能大约为14.56 kJ/mol.