Lattice Matching Dictates the Growth Mode and Quality of Deuterium Crystallization in Confined Spherical Shells
Abstract
Cryogenic hydrogen isotope fuel layers with high structural integrity and atomic-scale smoothness are prerequisites for symmetric implosion and ignition in inertial confinement fusion (ICF). Using deuterium (D2) as model fuel, we perform large-scale molecular dynamics simulations with a Feynman-Hibbs corrected Silvera-Goldman potential to describe nuclear quantum effects at low temperatures, systematically investigating D2 crystallization inside spherical ablator capsules. By varying substrate lattice constant from 3.1 angstrom to 3.9 angstrom, we demonstrate that lattice matching dictates the transition from coherent epitaxial growth to polycrystalline formation, establishing it as the primary design principle for high-performance targets. When the substrate lattice closely matches the equilibrium hexagonal-close-packed (HCP) spacing of cryogenic D2 (approximately 3.5 angstrom), D2 forms coherent layer-by-layer epitaxial growth consistent with Ostwald's stepwise nucleation theory, yielding HCP-dominated near-single crystals with minimal dislocations and ultra-smooth inner surfaces. In contrast, large lattice mismatch destabilizes coherent growth and causes island-like growth, producing polycrystalline structures with mixed HCP/FCC phases, elevated defects, and greatly increased surface roughness. Radial stress analysis shows that interfacial stress from mismatch localizes within 2-3 molecular layers near the interface, triggering subsequent defect-mediated growth. These findings highlight substrate lattice matching in regulating confined solid growth and crystallization quality, establish it as a key principle for ablator inner-surface engineering in ICF cryogenic targets, and offer atomic guidance for growing high-quality single-crystal deuterium-tritium (DT) fuel layers with optimal smoothness.
Versions
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BibTeX
@misc{bi2026lattice,
title = {{Lattice Matching Dictates the Growth Mode and Quality of Deuterium Crystallization in Confined Spherical Shells}},
author = {Peng Bi and Yu-Shen Wan and Wei Zhang and Jian Chen and Yong Yi and Qi-Feng Chen},
howpublished = {arXiv},
year = {2026},
month = jun,
doi = {10.48550/arxiv.2606.16550},
eprint = {2606.16550},
archivePrefix = {arXiv},
url = {https://arxiv.org/abs/2606.16550},
note = {CC BY-NC-ND 4.0},
}
RIS
TY - UNPB
TI - Lattice Matching Dictates the Growth Mode and Quality of Deuterium Crystallization in Confined Spherical Shells
AU - Peng Bi
AU - Yu-Shen Wan
AU - Wei Zhang
AU - Jian Chen
AU - Yong Yi
AU - Qi-Feng Chen
PY - 2026
DA - 2026/06/17
PB - arXiv
DO - 10.48550/arxiv.2606.16550
UR - https://arxiv.org/abs/2606.16550
AB - Cryogenic hydrogen isotope fuel layers with high structural integrity and atomic-scale smoothness are prerequisites for symmetric implosion and ignition in inertial confinement fusion (ICF). Using deuterium (D_2) as model fuel, we perform large-scale molecular dynamics simulations with a Feynman-Hibbs corrected Silvera-Goldman potential to describe nuclear quantum effects at low temperatures, systematically investigating D_2 crystallization inside spherical ablator capsules. By varying substrate lattice constant from 3.1 angstrom to 3.9 angstrom, we demonstrate that lattice matching dictates the transition from coherent epitaxial growth to polycrystalline formation, establishing it as the primary design principle for high-performance targets. When the substrate lattice closely matches the equilibrium hexagonal-close-packed (HCP) spacing of cryogenic D_2 (approximately 3.5 angstrom), D_2 forms coherent layer-by-layer epitaxial growth consistent with Ostwald's stepwise nucleation theory, yielding HCP-dominated near-single crystals with minimal dislocations and ultra-smooth inner surfaces. In contrast, large lattice mismatch destabilizes coherent growth and causes island-like growth, producing polycrystalline structures with mixed HCP/FCC phases, elevated defects, and greatly increased surface roughness. Radial stress analysis shows that interfacial stress from mismatch localizes within 2-3 molecular layers near the interface, triggering subsequent defect-mediated growth. These findings highlight substrate lattice matching in regulating confined solid growth and crystallization quality, establish it as a key principle for ablator inner-surface engineering in ICF cryogenic targets, and offer atomic guidance for growing high-quality single-crystal deuterium-tritium (DT) fuel layers with optimal smoothness.
ER -