Interatomic Potentials For Zr Metal

Molecular dynamics simulation is a key theoretical tool for the understanding ofthe microscopic mechanisms at the atomic level including the study of phasetransition, plastic deformation et.al. which utilize the hundreds of millions of atomsmolecular dynamics simulation. Zirconium has high strength and toughness and it isalso widely used as the nuclear material. Especially, the molecular dynamicssimulation is widely used to study the properties of the material. Interatomic Potentialis a key foundation of molecular dynamics simulation. The deformation way ofZirconium is different from other close-packed hexagonal metal which is the basalslip, while{1010}prismatic slip is the main way of Zirconium and Zirconium alloysat different temperature range. The current problem is the stacking fault energy ofbasal slip calculated through the existing potential function is lower than that fromprismatic slip and the plastic deformation mechanism of zirconium and zirconiumalloys can not be described by this kind of potential function.There are a lot of models of Interatomic Potentials, for example, the pairpotential model and the many-body potential model. The pair potential model ismainly used to study the inorganic compounds except the metal and semiconductor.In the many-body potential model, the embedded atom method (EAM) model and theFinnis-Sinclair potential model are more representative. EAM potential model ismainly used to study the simple precious metals of the small bond orientation, but itdoes not apply to the middle part of the transition group elements. Finnis-Sinclairpotential model is mainly used to study the pure metals, the binary alloys and theintermetallic compounds, particularly, it is appropriate for the fcc the structure ofmetals.In this paper, the Interatomic Potential models and the range of application areintroduced. We focus on the embedded atom potential model and construct theinteratomic EAM potential of Zr. The experimental data of the lattice constant, thecohesive energies,the vacancy formation energy, the elastic constants, the bulkmodulus, and the average shear modulus is used to fit the EAM potential of the pure metal Zr, which provides a reliable potential function to study the plastic deformationprocess of Zr in the atomic level.In order to examine the rationality of the potential function built in this paper,Wecompare the result with the Rose curve, and find that the curve which is truncated isagree with Rose curve. The potential function are used to calculate elastic constants,bulk modulus, average shear modulus and cohesive energies and compare them theinput values. The relative error obtained is within a reasonable range.In this paper, the structural stability of the potential function is examined. Andthe cohesive energy of hcp structure, bcc structure and fcc structure is calculatedunder the condition of the same volumes. The result shows that the cohesive energyof bcc structure is the highest but the most unstable. The cohesive energy of fccstructure and hcp structure are close to each other and the fcc structure cohesiveenergy is a little lower. This result can be understood because the hcp structure andfcc structure are both the close-packed structures, the arrangement mode of the firsttwo layers of atoms is the same in the close-packed plane and the cohesive energiesof them are close to each other when the truncation distances are closer.To examine the potential function further, the vacancy formation energy of Zrhas been calculated in this paper, experimental and calculated values agree well.