Materials Modelling Division

Revealing the impact of defects on anti-ferroelectric loops

We present a method which allows to solve the charge neutrality condition while accounting for defect quenching and fixed dopant concentrations, without neglecting the dependency of their charge state on electron chemical potential and temperature.

Members of MM division and MPIE reveal the origin

Atomistic computer simulations reproduce the jerky dislocation motion with repeated pinning in random samples without short-range order.The underlying mechanism is directly linked to local fluctuations in Peierls (force/friction) barriers, which lead to dislocation pinning points. The quantification of atomic frictional forces provides predictive design guidelines to tailor dislocation pinning in HEAs.

Fermi level engineering of antiferroelectrics

Antiferroelectric NaNbO3 is a candidate material for application in high-energy density dielectric capacitors. In this context, various doping strategies have been used for installing the desired narrow double P–E loop behavior in this lead-free material. However, controlled doping requires a detailed understanding of the type and population of intrinsic defects.

A machine-learned interatomic potential for silica and its relation to empirical models

Silica (SiO2) is an abundant material with a wide range of applications. Despite much progress, the atomistic modelling of the different forms of silica has remained a challenge. Here we show that by combining density-functional theory at the SCAN functional level with machine-learning-based interatomic potential fitting, a range of condensed phases of silica can be accurately described.

An Atomistic Investigation

The dissociation of short-lived excitons gives rise to free electrons and holes. If coupled with the motion of nuclei, these free charges get trapped at a lattice site and polarons form. Due to the involvement of lattice distortions in the formation of polarons, their lifetime exceeds that of excitons. In this study polaron formation and migration in PbTiO3 is addressed.