An interatomic model potential for molecular dynamics is derived from first-principles and used to study the molecular rotations and relaxation times in methylammonium lead halide, here considered the prototypical example of a hybrid crystal with a strong reorientational dynamics. Within the limits of a simple ionic scheme, the potential is able to catch the main qualitative features of the material at zero and finite temperature and opens the way to the development of classical potentials for hybrid perovskites. In agreement with experiments and previous theoretical findings, the molecule trajectories exhibit a transition from a dynamics dominated by high symmetry directions at low temperature to a fast dynamics at room temperature in which the molecule can reorient quasi-randomly. By computing the angular time correlation function we discuss the reorientational time as a function of temperature in comparison with existing literature, providing a simple model and a clear attribution of the relaxation times in terms of their temperature dependence. This work clarifies the temperature dependence of the relaxation times and the interpretation of the experimental data in terms of the different mechanisms contributing to the molecule dynamics.

Methylammonium rotational dynamics in lead halide perovskite by classical molecular dynamics: the role of temperature

FILIPPETTI, ALESSIO;DELUGAS, PIETRO DAVIDE
2015

Abstract

An interatomic model potential for molecular dynamics is derived from first-principles and used to study the molecular rotations and relaxation times in methylammonium lead halide, here considered the prototypical example of a hybrid crystal with a strong reorientational dynamics. Within the limits of a simple ionic scheme, the potential is able to catch the main qualitative features of the material at zero and finite temperature and opens the way to the development of classical potentials for hybrid perovskites. In agreement with experiments and previous theoretical findings, the molecule trajectories exhibit a transition from a dynamics dominated by high symmetry directions at low temperature to a fast dynamics at room temperature in which the molecule can reorient quasi-randomly. By computing the angular time correlation function we discuss the reorientational time as a function of temperature in comparison with existing literature, providing a simple model and a clear attribution of the relaxation times in terms of their temperature dependence. This work clarifies the temperature dependence of the relaxation times and the interpretation of the experimental data in terms of the different mechanisms contributing to the molecule dynamics.
Physical and theoretical chemistry; Electronic, optical and magnetic materials; Surfaces, coatings and films; Energy (all)
File in questo prodotto:
File Dimensione Formato  
Mattoni JPCC 2015.pdf

Solo gestori archivio

Tipologia: versione editoriale
Dimensione 5.11 MB
Formato Adobe PDF
5.11 MB Adobe PDF   Visualizza/Apri   Richiedi una copia

I documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.

Utilizza questo identificativo per citare o creare un link a questo documento: https://hdl.handle.net/11584/191690
Citazioni
  • ???jsp.display-item.citation.pmc??? ND
  • Scopus 202
  • ???jsp.display-item.citation.isi??? 205
social impact