%0 Journal Article
%A Seijas-Bellido, Juan Antonio
%A Samanta, Bipasa
%A Valadez-Villalobos, Karen
%A Gallardo, Juan Jesús
%A Navas, Javier
%A Balestra, Salvador
%A Madero Castro, Rafael María
%A Vicent-Luna, Jose Manuel
%A Tao, Shuxia
%A Caspary Toroker, Maytal
%A Anta, Juan A.
%T Transferable Classical Force Field for Pure and Mixed Metal Halide Perovskites Parameterized from First-Principles
%D 2022
%@ 1549-9596
%U http://hdl.handle.net/10433/13900
%X Many key features in photovoltaic perovskites occur
in relatively long time scales and involve mixed compositions. This
requires realistic but also numerically simple models. In this work
we present a transferable classical force field to describe the mixed
hybrid perovskite MAxFA1¿xPb(BryI1¿y)3 for variable composition
(¿x, y ¿ [0, 1]). The model includes Lennard-Jones and
Buckingham potentials to describe the interactions between the
atoms of the inorganic lattice and the organic molecule, and the
AMBER model to describe intramolecular atomic interactions.
Most of the parameters of the force field have been obtained by
means of a genetic algorithm previously developed to parametrize
the CsPb(BrxI1¿x)3 perovskite (Balestra et al. J. Mater. Chem. A.
2020, DOI: 10.1039/d0ta03200j). The algorithm finds the best parameter set that simultaneously fits the DFT energies obtained for
several crystalline structures with moderate degrees of distortion with respect to the equilibrium configuration. The resulting model
reproduces correctly the XRD patterns, the expansion of the lattice upon I/Br substitution, and the thermal expansion coefficients.
We use the model to run classical molecular dynamics simulations with up to 8600 atoms and simulation times of up to 40 ns. From
the simulations we have extracted the ion diffusion coefficient of the pure and mixed perovskites, presenting for the first time these
values obtained by a fully dynamical method using a transferable model fitted to first-principles calculations. The values here
reported can be considered as the theoretical upper limit, that is, without grain boundaries or other defects, for ion migration
dynamics induced by halide vacancies in photovoltaic perovskite devices under operational conditions.
%K Classical Molecular Dynamics
%K Metal-halide perovskites
%~ GOEDOC, SUB GOETTINGEN