Scaled and Dynamic Optimizations of Nudged Elastic Bands

Abstract

We present a modified nudged elastic band routine that can reduce the number of force calls by more than 50% for bands with non-uniform convergence. The method, which we call "dyNEB", dynamically and selectively optimizes states based on the perpendicular PES-derived forces and parallel spring forces acting on that region of the band. The convergence criteria are scaled to focus on the region of interest, i.e., the saddle point, while maintaining continuity of the band and avoiding truncation. We show that this method works well for solid state reaction barriers-nonelectrochemical in general and electrochemical in particular-and that the number of force calls can be significantly reduced without loss of resolution at the saddle point.

Generalizable Trends in Electrochemical Protonation Barriers

“…Electrochemical reaction barriers pose added challenges for accurately modeling processes at constant potential within the constraints of typical simulation methods, such as finite unit cell sizes in constant charge computations or inaccuracies arising from continuum models. − Furthermore, despite continued advances in both computational resources and modeling algorithms, − determining activation barriers of reactions via typical methods like nudged elastic band with ab initio electronic structure simulations often comes at significant costs. , Given the challenges and considerable resources required to compute electrochemical reaction barriers, generalizeable trends in activation energies of proton-coupled electron transfers (PCET) can provide useful insights and intuition when modeling reactive processes. For instance, understanding the relative difficulty of transferring a proton to carbon versus oxygen would aid in predicting plausible reaction pathways in complex processes, such as CO 2 reduction …”

Polaron-Assisted Charge Transport in Li-Ion Battery Anode Materials

“…All DFT calculations have been carried out using the FHI-aims electronic structure code . Nudged elastic band (NEB) calculations have been performed using the atomic simulation environment by applying scaled and dynamic optimization for a pre-optimization of the Li migration path. − Final pathways were then recalculated without dynamic optimization.…”

Sodium effects on the electronic and structural properties of porous silicon for energy storage

“…In each geometrical optimization, the atomic forces were set to be less than0.04 eV/Å, while the tolerance in each element of the density matrix for the self-consistent algorithm was set to be 10 À4 eV. We have calculated the transition state and the activation energy on hydrogen passivated porous silicon, using the nudged elastic band (NEB) method [75][76][77][78][79] implemented in the Siesta code subroutine. The NEB is a chain-of-states iterative method in which a string of discrete sets of configurations of all the atoms in the system is used to describe a reaction pathway.…”