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Title: Local volume effects in the generalized pseudopotential theory

Journal Article · · Physical Review B
 [1];  [1];  [2]
  1. King's College London (United Kingdom)
  2. Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States)

The generalized pseudopotential theory (GPT) is a compelling approach for deriving real-space transferable interatomic potentials. Using a coarse-grained electronic structure, one can explicitly determine the pair ion-ion and multi-ion interactions in simple and transition metals. While successful in determining bulk properties, in central force metals the GPT fails to describe crystal defects for which there is a significant local volume change. A previous paper [J. A. Moriarty and R. Phillips, Phys. Rev. Lett. 66, 3036 (1991)] found that by allowing the GPT total energy to depend upon some spatially averaged local electron density, the energetics of vacancies and surfaces could be calculated within experimental ranges. In this paper, we develop the formalism further by explicitly calculating the forces and stress tensor associated with this total energy. We call this scheme the adaptive GPT (aGPT) and it is capable of both molecular dynamics (MD) and molecular statics. We apply the aGPT to vacancy formation, divacancy binding, and stacking faults in hcp Mg. We also calculate the local electron density corrections to the bulk elastic constants and phonon dispersion for which there is refinement over the baseline GPT treatment. Furthermore, we demonstrate aGPT-MD simulation through the calculation of thermal expansion in magnesium to 700 K.

Research Organization:
Lawrence Livermore National Laboratory (LLNL), Livermore, CA (United States)
Sponsoring Organization:
USDOE National Nuclear Security Administration (NNSA)
Grant/Contract Number:
AC52-07NA27344
OSTI ID:
1557065
Report Number(s):
LLNL-JRNL--761045; 949102
Journal Information:
Physical Review B, Journal Name: Physical Review B Journal Issue: 21 Vol. 99; ISSN 2469-9950; ISSN PRBMDO
Publisher:
American Physical Society (APS)Copyright Statement
Country of Publication:
United States
Language:
English

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