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Bond-Order Potentials with Analytic Environment-Dependent Tight-Binding Integrals: Application to BCC Molybdenum

Published online by Cambridge University Press:  21 March 2011

Matous Mrovec ,
Duc Nguyen-Manh ,
David G. Pettifor  and
Vaclav Vitek
Matous Mrovec
Affiliation:
Department of Materials Science and Engineering, University of Pennsylvania, Philadelphia, PA 19104-6272, U.S.A.
Duc Nguyen-Manh
Affiliation:
Department of Materials, University of Oxford, Parks Road, Oxford OX1 3PH, United Kingdom
David G. Pettifor
Affiliation:
Department of Materials, University of Oxford, Parks Road, Oxford OX1 3PH, United Kingdom
Vaclav Vitek
Affiliation:
Department of Materials Science and Engineering, University of Pennsylvania, Philadelphia, PA 19104-6272, U.S.A.
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Abstract

We present a new Screened Bond-Order Potential (SBOP) for molybdenum in which the environmental dependence of two-center tight-binding bond integrals has been implemented via a recently developed analytic expression. These bond integrals reproduce very well the numerical ab-intio values of screened LMTO bond integrals. In particular, they display the large discontinuity in ddπ between the first and second nearest neighbor of the bcc lattice whereas they do not show any discontinuity in ddσ. This dependence can be traced directly to the angular character of the analytic screening function and is shown to be critical for the behavior of the second nearest neighbor force constants. The new BOP eliminates the problem of the very soft T2 phonon mode at the N point that is found in most two-center tight-binding models. Preliminary study of the core structure of 1/2<111> screw dislocations performed using SBOP indicates that the core is narrower and less asymmetric than structures found in previous studies, in agreement with recent ab-initio calculations.

Type
Research Article
Information
MRS Online Proceedings Library (OPL) , Volume 653: Symposium Z – Multiscale Modeling of Materials-2000 , 2000 , Z6.3.1
Copyright
Copyright © Materials Research Society 2001

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