Classical Force-Field Parameters for CsPbBr₃ Perovskite Nanocrystals

Abstract

Understanding the chemico-physical properties of colloidal semiconductor nanocrystals (NCs) requires exploration of the dynamic processes occurring at the NC surfaces, in particular at the ligand–NC interface. Classical molecular dynamics (MD) simulations under realistic conditions are a powerful tool to acquire this knowledge because they have good accuracy and are computationally cheap, provided that a set of force-field (FF) parameters is available. In this work, we employed a stochastic algorithm, the adaptive rate Monte Carlo method, to optimize FF parameters of cesium lead halide perovskite (CsPbBr 3 ) NCs passivated with typical organic molecules used in the synthesis of these materials: oleates, phosphonates, sulfonates, and primary and quaternary ammonium ligands. The optimized FF parameters have been obtained against MD reference trajectories computed at the density functional theory level on small NC model systems. We validated our parameters through a comparison of a wide range of nonfitted properties to experimentally available values. With the exception of the NC–phosphonate case, the transferability of the FF model has been successfully tested on realistically sized systems (>5 nm) comprising thousands of passivating organic ligands and solvent molecules, just as those used in experiments.

Piezo-responsive bismuth ferrite nanoparticle-mediated catalytic degradation of rhodamine B and pathogenicE. coliin aqueous medium and its extraction using external magnetic stimulation after successful treatment

“…Initially, the energy of the model was minimized using the universal force field (UFF) along with the steepest descent algorithm. 36…”

“…Initially, the energy of the model was minimized using the universal force field (UFF) along with the steepest descent algorithm. 36 Thereafter, the model was transferred into Orca v.4.2 for optimization of geometry and frequencies using density functional theory (DFT). 37 Herein, the Becke 3-parameter Lee-Yang-Parr (B3LYP) and def2-SVP functionals were used along with the 6-311G* basis set.…”

Classical Force Field Parameters for InP and InAs Quantum Dots with Various Surface Passivations

“…The optimization of the FF parameters was done analogously to the procedure described previously for CsPbBr 3 perovskite nanocrystals. 42 The ARMC optimization procedure has been described in much detail previously. 41 Following is roughly how the algorithm works (see Scheme 1).…”

“…While the potential energy is strongly influenced by long-range electrostatic (q i ) and short-range repulsive (σ ij ) terms, changes in the well-depth ε ij are known to contribute less energetically. 41,42 For this reason, the ε ij values are taken from the universal force field (UFF) 77 and kept fixed during the ARMC fitting (as described in detail below). Hence, only the atomic charges q i and the interatomic distances σ ij for the interactions between {1−1} and {1−2} are fitted.…”

Ligand Effects in Assembly of Cubic and Spherical Nanocrystals: Applications to Packing of Perovskite Nanocubes

“…All-atom force fields, with explicit consideration of hydrogen atoms and electric charges, should prevent these effects. Although most widely used force fields are designed for situations that are quite different than the ones relevant in the process of solvent evaporation, it is worth pointing recent developments specifically designed for perovskites, which are more appropriate for the type of calculations presented in this paper.…”