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THU: Thursday Contributed Sessions

THU 13: Poster Session: Applications

THU 13.92: Poster

Donnerstag, 11. September 2025, 16:30–18:30, ZHG Foyer 1. OG

Accurate modeling of polarization in large-scale molecular dynamics simulations — •Hikaru Azuma¹, Shuji Ogata¹, Ryo Kobayashi¹, Masayuki Uranagase², Yuta Takahashi¹, and Takahiro Tsuzuki¹ — ¹Nagoya Institute of Technology, Japan — ²Riken, Japan

First-principles calculations yield the polarization, dielectric, and piezoelectric responses, which serve as indicators of the ferroelectric material's performance. However, these properties depend strongly on temperature in experiments. For instance, in BaTiO3, the polarization direction changes through successive phase transitions as temperature increases. Classical molecular dynamics simulations that assign point charges to atoms provides only a rough estimate of polarization based on atomic displacements. First-principles calculations reveal that each atom's contribution is anisotropic and varies dynamically with its environment. This variation is quantified by the Born effective charge, which is a feature that a fixed point-charge model cannot capture. The shell model includes these effects using multiple point charges to an atom but underestimate polarization-related properties.

Here, we perform MD simulations using a novel hybrid interatomic potential that combines a shell model with a machine-learning potential. Our model accurately reproduces BaTiO3's phase transitions and improves polarization predictions. We examine how precise modeling of polarization and Born effective charges affects predictions of the temperature dependence of the dielectric and piezoelectric responses.

Keywords: Polarization; Molecular dynamics; First-principles calculations; Ferroelectrics