N2H4在NiFe(111)合金表面吸附稳定性和电子结构的第一性原理研究

采用基于色散校正的密度泛函理论进行了第一性原理研究, 详细分析了肼(N₂H₄)在Ni₈Fe₈/Ni(111)合金表面稳定吸附构型的吸附稳定性和电子结构及成键性质. 通过比较发现, 肼分子以桥接方式吸附在表面的两个Fe原子上是最稳定的吸附构型, 其吸附能为-1.578 eV/N₂H₄. 同时发现, 肼分子在这一表面上吸附稳定性的趋势为: 桥位比顶位吸附更有利, 且在Fe原子上比在Ni原子上的吸附作用更强. 进一步分析了不同吸附位点上稳定吸附构型的电子结构、电荷密度转移以及电子局域化情况. 结果发现: 相同吸附位点的电子态密度图基本一致, 并且N原子的p轨道和与之相互作用的表面原子的d轨道之间存在态密度上的重叠; 吸附后电荷密度则主要从肼分子转移到表面原子之上; 在电子局域化函数切面图中也发现吸附后电子被局域到肼分子的N原子和相邻的表面原子之间. 这些电子结构的表征都充分说明肼分子与表面原子之间通过电荷转移形成了强烈的配位共价作用.     

Generalized hyperelliptic surfaces

This article presents some results on the surfaces of general type whose Albanese morphism is a holomorphic fibre bundle.

     

of Hamiltonian manifolds

Let be a connected, compact symplectic manifold equipped with a Hamiltonian action. We prove that, as fundamental groups of topological spaces, , where is the symplectic quotient at any value in the image of the moment map .

     

Hard-sphere binary-collision operators

The time displacement operator is described for a system of hard-sphere particles. We show how to avoid needing a representation for this operator in unphysical regions of phase space, and how to construct a useful representation in terms of binary collision operators in the physical region. The various binary collision operators used for hard-sphere systems are derived for the case of a system of two spheres, and the results are generalized toN-particle systems.Dedicated to Prof. E. G. D. Cohen on the occasion of his 65th birthday.     

LocalH-theorem for a kinetic variational theory

A localH-theorem is derived for a recently proposed extension of Enskog kinetic theory to a dense model fluid composed of particles with interactions extending beyond a hard core.On leave from: Katedra Fizyki, Uniwersytetu Szczecinskiego, 70-451 Szczecin, Poland.     

An alternative approach to investigate the origin of p-type conductivity in arsenic doped ZnO

P-type conductivity in MOCVD grown ZnO was obtained by directional thermal diffusion of arsenic from semi-insulating GaAs substrate. The films were single crystalline in nature and oriented along (002) direction. Ab initio calculations in the framework of density functional theory have been carried out with different chemical states of arsenic in ZnO. Present calculations suggested As_Zn–2V_Zn defect is a shallow acceptor and results in ferromagnetism in ZnO. The magnetic measurements of the samples indeed showed ferromagnetic ordering at room temperature. X-ray photoelectron spectra confirmed the presence of As_Zn and V_Zn. The core level chemical shift in binding energy of As_Zn indicated the formation of As_Zn–2V_Zn. Diffused arsenic substitutes zinc atom and creates additional zinc vacancies. The zinc vacancies, surrounding the oxygen atoms, result in unpaired O 2p electrons which in turn induce ferromagnetism in the samples.     

The geometry structures and electronic properties of Li_mB_n(m+n=12) clusters

The geometric structures, electronic properties, total and binding energies, harmonic frequencies, the highest occupied molecular orbital to the lowest unoccupied molecular orbital energy gaps, and the vertical ionization potential energies of small LimBn （m＋ n = 12） clusters were investigated by the density functional theory B3LYP with a 6-31 I＋G （2d, 2p） basis set. All the calculations were performed using the Gaussian09 program. For the study of the LimBn clusters, the global minimum of the B 12 cluster was chosen as the starting point and the boron atoms were gradually replaced by Li atoms. The results showed that as the number of Li atoms increased, the stability of the LimBn cluster decreased and the physical and chemical properties became more active. In addition, on average there was a large charge transfer from the Li atoms to the B atoms.     

1,1-二氨基-2,2-二硝基乙烯晶体热膨胀各向异性的模拟研究

对新型钝感高能炸药组分1,1-二氨基-2,2-二硝基乙烯（FOX-7）,考察并选择了适用的分子力场和超晶胞初始构型,通过303K-378K温度范围在NPT系综下的分子动力学模拟（MD）,得到常压下各温度的FOX-7晶体平衡构型,发现随温度升高晶体内分子的取向和堆积方式不变;通过线性拟合求算出线膨胀系数,发现αb明显较大而αc与αa接近但不相等;接着采用密度泛函理论(DFT)方法随各向棱长膨胀的能量变化进行了模拟计算,发现得到的能量变化成各向异性并与各向热膨胀系数相关,从而建立FOX-7晶体特定分子堆积模式与热膨胀各向异性的关联。     

MgnLa(n=2-6)掺杂团簇的密度泛函研究

采用密度泛函(DFT)中的B3LYP方法,选择CEP-31g基组,优化并得到了MgnLa(n=2- 6)小团簇的基态平衡结构,计算出了掺杂团簇的基态结构的平均键长、对称性、费米能级、能级间隙、束缚能、总能的二阶差分．结果表明,随着团簇原子数的增加,La原子更容易趋于团簇表面位置. 与未掺杂Mg团簇相比,La原子多采用取代其稳定基态结构的一个Mg原子形成掺杂团簇的稳定结构. 从有限的结果看,其中 Mg3La和 Mg6La的结构更为稳定．     

Automated derivation of optimal regulators for nonlinear systems by symbolic manipulation of Poisson series

Concepts of programmability and compact programmability are defined relative to a class of modified Poisson series. Lie-series-based canonical perturbation methods from astrodynamics are applied to the Hamiltonian system boundary-value problem, and more usual methods are applied to the perturbed Hamilton-Jacobi-Bellman partial differential equation, in order to obtain a complete set of equations for the perturbed optimal feedback control law for both infinite-time and finite-time regulator problems. The relative advantages of each approach are evaluated. A major aim of the paper is to determine the largest class of perturbations, within the set of Poisson series, for which the equations can be derived on a computer by symbolic manipulation. The more general the class, the more accurate the perturbation solution can be, for a given order. The solutions developed are complete; all that remains is to program them in order to have computerized derivations of the optimal nonlinear feedback control laws.This research was supported by NSF Grant No. ENG-78-10232. This paper was presented at the 1982 Conference on Information Sciences and Systems, Princeton, New Jersey, and appears in the Proceedings.