The lattice-inversion embedded-atom-method interatomic potential developed previously by us is extended to alkaline metals including Li,Na,and K.It is found that considering interatomic interactions between neighboring atoms of an appropriate distance is a matter of great significance in constructing accurate embedded-atom-method interatomic potentials,especially for the prediction of surface energy.The lattice-inversion embedded-atom-method interatomic potentials for Li,Na,and K are successfully constructed by taking the fourth-neighbor atoms into consideration.These angular-independent potentials markedly promote the accuracy of predicted surface energies,which agree well with experimental results.In addition,the predicted structural stability,elastic constants,formation and migration energies of vacancy,and activation energy of vacancy diffusion are in good agreement with available experimental data and first-principles calculations,and the equilibrium condition is satisfied.
本文中,我们用新的晶格反演方法获得了系列原子间相互作用势;用晶格反演方法改进EAM(Embedded Atom Method,嵌入原子方法)势,并对晶格反演EAM势和多重晶格反演EAM势进行了探索,对Ni-Al、Fe-Al、Co-Al、Ti-Al等二元合金的力学及热力学性质进行了原子级模拟计算。我们采用晶格反演方法获得层状材料的层间势,重点对石墨烯材料进行了研究。同时,我们用第三类晶格反演方法获得各种金属/化合物界面原子相互作用势并进行了系列性应用,并利用晶格反演对势在金属间化合物中进行应用拓展,对重要的稀土和锕系金属间化合物的结构和热力学性质进行了原子级模拟计算。这对含有无序子晶格结构体系的处理提供了新的方法。
Aiming at developing p-type semiconductors and modulating the band gap for photoelectronic devices and band engineering,we present the ab initio numerical simulation of the effect of codoping ZnO with Al,N and Mg on the crystal lattice and electronic structure.The simulations are based on the Perdew-Burke-Ernzerhof generalised-gradient approximation in density functional theory.Results indicate that electrons close to the Fermi level transfer effectively when Al,Mg,and N replace Zn and O atoms,and the theoretical results were consistent with the experiments.The addition of Mg leads to the variation of crystal lattice,expanse of energy band,and change of band gap.These unusual properties are explained in terms of the computed electronic structure,and the results show promise for the development of next-generation photoconducting devices in optoelectronic information science and technology.
The structural properties,the enthalpies of formation,and the mechanical properties of some Ni-Al intermetallic compounds(NiAl,Ni3Al,NiAl3,Ni5Al3,Ni3Al4) are studied by using Chen's lattice inversion embedded-atom method(CLI-EAM).Our calculated lattice parameters and cohesive energies of Ni-Al compounds are consistent with the experimental and the other EAM results.The results of enthalpy of formation indicate a strong chemical interaction between Ni and Al in the intermetallic compounds.Through analyzing the alloy elastic constants,we find that all the Ni-Al intermetallic compounds discussed are mechanically stable.The bulk moduli of the compounds increase with the increasing Ni concentration.Our results also suggest that NiAl,Ni3Al,NiAl3,and Ni5Al3 are ductile materials with lower ratios of shear modulus to bulk modulus;while Ni3Al4 is brittle with a higher ratio.
Systematic approaches are presented to extract the interfacial potentials from the ab initio adhesive energy of the interface system by using the Chen–M ¨obius inversion method. We focus on the interface structure of the metal(111)/Zn O(0001)in this work. The interfacial potentials of Ag–Zn and Ag–O are obtained. These potentials can be used to solve some problems about Ag/Zn O interfacial structure. Three metastable interfacial structures are investigated in order to check these potentials. Using the interfacial potentials we study the procedure of interface fracture in the Ag/Zn O(0001) interface and discuss the change of the energy, stress, and atomic structures in tensile process. The result indicates that the exact misfit dislocation reduces the total energy and softens the fracture process. Meanwhile, the formation and mobility of the vacancy near the interface are observed.
The site preferences of the rare earth intermetallics Nd6Fe13-xTxSi(T = Co, Ni) are investigated by using interatomic pair potentials which are converted from a lattice-inversion method. Calculation shows that the order of the site preference of Co is 4d, 16 k, 16l1, and 16l2 and that of Ni is 16l2, 16l1, 16 k, and 4d in Nd6Fe13-xTxSi. Calculated lattice and positional parameters are found to agree with those reported in the literature. Furthermore, the phonon density of states for Nd6Fe13-xTxSiis also evaluated, and a qualitative analysis featuring the coordination and the relevant potentials is carried out.
The surface geometry,electronic structure,and magnetism of Eu@C 60 monolayer absorbed on Ag(111) have been investigated within the framework of density functional theory.The Eu@C 60 monolayer has been constructed on Ag(111) substrate by one of the hexagon faces of C 60 downward and its mirror plane face parallel to Ag(111).The Eu@C 60 monolayer induces a reconstruction of the Ag(111) substrate and the perpendicular distance between the Eu@C 60 and Ag(111) surface is 2.06,being shorter than that between C 60 and Ag(111) surface by 0.05.There is no chemical bond formed between the Eu@C 60 and Ag(111),and only 0.55e transferred from Ag(111) to Eu@C 60.A large magnetic moment about 6.80 B per unit cell is found for Eu@C 60 /Ag(111) system.
