AI and the World's Hard Problems · Physics · arXiv · 2026-10-19
Angular compliance, not amplitude, governs the dielectric response of BaTiO3
Soft-mode theory gives a frequency but does not specify what real-space motion of local polar units underlies the dielectric response of BaTiO3. Using electric-field-induced molecular dynamics with a machine-learning force field, the authors show that permittivity follows the field-induced angular redistribution of local Ti-O off-centering rather than its magnitude. Temperature and biaxial strain change the local structure by different routes, yet both responses collapse onto one relation with the same orientational descriptor, offering a real-space counterpart to soft-mode behavior.