The Problems of the Construction of Many-Body Potentials

Mikhail D. Starostenkov ,  Gennadiy M. Poletaev 

Altai State Technical University (ASTU), Lenin st.46, Barnaul 656038, Russian Federation

Abstract

One of the most important conditions of a realistic simulation of the processes taking place in metals and alloys at an atomic level is a proof description of interatomic interactions. The most wide-spread potentials at present time are many-body Finnis-Sinclair potentials and potentials, obtained by the embedded atom method. The advantage of many-body potentials in comparison with pair ones is their validity from the point of view of solid state theory. The potential energy of the system of atoms is presented as the sum of contribution of atoms pair interactions and many-body contribution identified with the energy of conductivity electrons. The use of Finnis-Sinclair potentials in the work showed that there was one essential drawback in the methods of the construction of many-body potentials. The problem is in the absence of reliable criterion to evaluate the contribution of many-body part of atoms interaction energy during the calculation of potential parameters. The only criterion that can define the contribution is the Cauchy pressure (the other characteristics can be described by a pair potential). But, the calculation values of elastic modules, as a rule, are not exactly corresponded to experimental data and the Cauchy pressure is calculated with an error. Besides, this criterion is corresponded to an ideal crystal lattice. That is why the contribution of many-body component of a structure near a defect can not be evaluated beyond all doubt. In this connection, many-body component of potential can have underestimated or overestimated contribution. In the first case, many-body potentials behave like pair potentials, and the results obtained with their use slightly differ from the results obtained by pair potentials. In the second case, metal structures tend to the increasing of coordination number (local density), sometimes even in damage to a long order of crystal because of the excessive contribution of many-body component.

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Presentation: Poster at E-MRS Fall Meeting 2008, Symposium G, by Mikhail D. Starostenkov
See On-line Journal of E-MRS Fall Meeting 2008

Submitted: 2008-05-19 09:16
Revised:   2009-06-07 00:48
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