Barium titanate (BTO) is a representative perovskite oxide that undergoes three first-order ferroelectric phase transitions related to exceptional functional properties. In this work, we develop two atomic cluster expansion (ACE) models for BTO to reproduce fundamental properties of bulk and defective BTO phases. The two ACE models do not target full transferability but rather aim to examine the influence of implicit and explicit treatment of long-range Coulomb interactions. We demonstrate that both models describe equally well the temperature-induced phase transitions and field-induced polarization switching. Even though the parametrizations are based on a limited number of configurations that are mostly not far away from the equilibrium, the ACE models are also able to capture properties of important crystal defects, such as oxygen vacancies, stacking faults, and domain walls. The phase transitions and the fundamental properties of the investigated defects can be described with similar accuracy with or without explicit treatment of charges and Coulomb interactions, allowing for efficient short-range machine learning potentials.

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• Domain walls
• Electric polarization
• Phase diagrams
• Phase transitions
• Vacancies