Numerical experiments on studying of microcrystal reaction on external power influences with application of a molecular dynamics method have been considered. A number of the dependences has been constructed, and these dependences show, that the microcrystal reaction is much differ from a macro sample reaction to the same external influences. Practically there are no linear curves on the received deformation diagrams, and this fact is evidence of qualitative influence of micro effects (for example, essentially nonlinear kind of particles interaction potential) on the whole microcrystal behavior.

For the first time the molecular dynamics simulation has been appeared in numerical physics at the end of fifties (B.J.Alder e T.E.Wainwright, 1959). For today it became a quite independent and rather powerful method of material microstructure investigation. Absolute practical efficiency of this method and simplicity of underlined assumptions allow to use this method successfully for a wide range of problems concerned with investigation of delicate microstructure of gases, fluids, molten metals, metals and polymers in a wide range of external parameters. In this project the use of molecular dynamic simulation for investigation of metal deformation properties on micro level has been attempted.

The aim of this research is a deformation diagrams construction and a getting of quantitative estimates of parameters responsible for material deformation properties. For that both perfect crystal and crystal with defects (including polycrystal) containing hundred atoms approximately has been considered. At the same time the problem of pattern behavior visualization for a wide range of temperature and deformation influences has been posed. That is why for this problem solution exactly the molecular dynamic simulation has been used.

This problem is important today because now there exists a need for physical relations which describe the mode of deformation and take into account the microstructure of material: nature of atomic bonding and defects kinetics including cracks and crystal boundaries. It is obvious, that for this problem solution it is necessary to have a method which allows to model the material behavior on micro level using computer simulation, since the realization of experiment in this case is closely related to great difficulties.

Scientific novelty of this work is bound up with the fact, that today majority of physical relations models authors try to switch from micro level to macro level using an averaging method. In papers where nevertheless the microstructure is concerned, only single physical elements (vacancies, dislocations, cracks and so on) are considered and their influence on deformation behavior of microcrystal is neglected.

As the first step in this work, the numerical simulation on forming of initial atomic structure for following calculations has been realized. It is worth mention that the necessity of such simulation has not a fundamental importance, since such initial structure can be formed manually. To a greater extent this simulation should be viewed as a test of calculation method.

In the next simulation the deformation properties of atomic configuration under deformation using isothermal boundary condition has been investigated. For this simulation approximately 500 atoms placed in equilibrium position (body-centered cubic cell) and filled the regular quadrangle have been considered. Atoms interaction has been described by Morse potential.

Practically there are no linear curves on the received deformation diagrams, and this fact is evidence of qualitative influence of micro effects (for example, essentially nonlinear kind of particles interaction potential) on the whole microcrystal behavior.

[1]	M.A.Kulesh and I.N.Shardakov Computer modeling of deformation properties of metals (in Russian) // PSTU Bulletin. Computational and Applied Mechanics. No. 1. P. 58-65 (1998). Full text (pdf, rus, 2437Kb)