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Updated: Feb 24, 2026
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Laser-heating and Radiance Spectrometry for the Study of Nuclear Materials in Conditions Simulating a Nuclear Power Plant Accident
Published on: December 14, 2017
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Atomistic Modeling of the Negative Thermal Expansion in δ- Plutonium Based on the Two-State Description
Tongsik Lee1, Michael I Baskes2,3, A C Lawson4
1Los Alamos National Laboratory, Los Alamos, NM 87545, USA. tongsik_lee@lanl.gov.
Materials (Basel, Switzerland)
|August 18, 2017
Summary
Researchers modeled plutonium
Area of Science:
- Materials Science
- Condensed Matter Physics
- Computational Materials Science
Background:
- The delta phase of plutonium (δ-Pu) exhibits negative thermal expansion (NTE) within a specific temperature range (593–736 K).
- Accurately modeling this anomalous volume behavior in plutonium is challenging for current electronic-structure calculations.
Purpose of the Study:
- To develop an atomistic model for predicting the thermodynamic properties of δ-Pu.
- To elucidate the mechanism behind the negative thermal expansion in δ-Pu.
Main Methods:
- An atomistic scheme incorporating a two-state model, inspired by Invar alloys, was developed.
- Two modified embedded atom method potentials were used to describe competing electronic states.
- Monte Carlo simulations were employed to implement the two-state mechanism and study thermal expansion.
Main Results:
- The proposed model successfully demonstrates the occurrence of negative thermal expansion in δ-Pu.
- The study provides insights into the thermodynamic behavior of δ-Pu based on competing electronic states.
Conclusions:
- The two-state atomistic model offers a viable approach for simulating the anomalous thermal expansion of δ-Pu.
- This work advances the understanding of complex materials behavior through atomistic simulations.
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