Reinterpretation of bond-valence model with bond-order formalism: an improved bond-valence based interatomic potential for PbTiO$_3$

TL;DR

This paper introduces an improved bond-valence model for PbTiO$_3$ that incorporates bond-order formalism, enabling accurate molecular dynamics simulations of phase transitions consistent with experimental observations.

Contribution

The authors derive a bond-order based bond-valence model for PbTiO$_3$ and introduce a new bond-valence vector energy term, enhancing the accuracy of atomistic simulations.

Findings

Reproduces experimental phase transition in NVT MD simulations.

Captures temperature-driven and pressure-driven phase transitions.

Potential applicable to various inorganic materials.

Abstract

We present a modified bond-valence model of PbTiO$_3$ based on the principles of bond-valence and bond-valence vector conservation. The relationship between the bond-valence model and the bond-order potential is derived analytically in the framework of a tight-binding model. A new energy term, bond-valence vector energy, is introduced into the atomistic model and the potential parameters are re-optimized. The new model potential can be applied both to canonical ensemble ($NVT$) and isobaric-isothermal ensemble ($NPT$) molecular dynamics (MD) simulations. This model reproduces the experimental phase transition in $NVT$ MD simulations and also exhibits the experimental sequence of temperature-driven and pressure-driven phase transitions in $NPT$ simulations. We expect that this improved bond-valence model can be applied to a broad range of inorganic materials.