On the relationship and distinction between atomic density and coordination number in describing crystal defects.
- 1Federal Institute for Materials Research and Testing (BAM) 12205 Berlin Germany [email protected].
- 2Institute of Materials Physics, University of Münster 48149 Münster Germany.
Abstract
Crystal defects are often described through broken atomic bonds, through counting the nearest neighbor coordination number. In this work, we highlight that the intrinsic heterogeneities in interatomic spacing due to a crystal defect, which is overlooked in broken-bond models, can decisively shape defect properties. We analyze excess free volume, energy, and entropy for a large set of BCC-Fe grain boundaries relaxed by molecular statics, and demonstrate that an atomic-density field, as a systematically coarse-grained field variable, shows much better correlations with the grain boundary properties. The atomic density field is shown to simultaneously capture bond depletion and spacing variations, thereby covering and unifying both structural and volumetric information. Our results establish the coarse-grained atomic density field as a principled surrogate for describing grain boundary thermodynamics, motivating the augmentation of broken-bond rules in predictive theories of interfacial energetics, excess properties, segregation, and phase behavior, and providing a direct bridge from atomistic to mesoscale models, with potential applications extending to other microstructural defects.
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BibTeX
@article{kamachali2026relationship,
title = {{On the relationship and distinction between atomic density and coordination number in describing crystal defects.}},
author = {Reza Darvishi Kamachali and Theophilus Wallis},
journal = {RSC advances},
year = {2026},
month = oct,
doi = {10.1039/d6ra05403j},
url = {https://europepmc.org/article/MED/42921201},
note = {CC BY},
}
RIS
TY - JOUR
TI - On the relationship and distinction between atomic density and coordination number in describing crystal defects.
AU - Reza Darvishi Kamachali
AU - Theophilus Wallis
PY - 2026
DA - 2026/10/23
JO - RSC advances
DO - 10.1039/d6ra05403j
UR - https://europepmc.org/article/MED/42921201
AB - Crystal defects are often described through broken atomic bonds, through counting the nearest neighbor coordination number. In this work, we highlight that the intrinsic heterogeneities in interatomic spacing due to a crystal defect, which is overlooked in broken-bond models, can decisively shape defect properties. We analyze excess free volume, energy, and entropy for a large set of BCC-Fe grain boundaries relaxed by molecular statics, and demonstrate that an atomic-density field, as a systematically coarse-grained field variable, shows much better correlations with the grain boundary properties. The atomic density field is shown to simultaneously capture bond depletion and spacing variations, thereby covering and unifying both structural and volumetric information. Our results establish the coarse-grained atomic density field as a principled surrogate for describing grain boundary thermodynamics, motivating the augmentation of broken-bond rules in predictive theories of interfacial energetics, excess properties, segregation, and phase behavior, and providing a direct bridge from atomistic to mesoscale models, with potential applications extending to other microstructural defects.
SN - 2046-2069
ER -