Highly energetic electron–hole pairs (hot carriers)
formed
from plasmon decay in metallic nanostructures promise sustainable
pathways for energy-harvesting devices. However, efficient collection
before thermalization remains an obstacle for realization of their
full energy generating potential. Addressing this challenge requires
detailed understanding of physical processes from plasmon excitation
in the metal to their collection in a molecule or a semiconductor,
where atomistic theoretical investigation may be particularly beneficial.
Unfortunately, first-principles theoretical modeling of these processes
is extremely costly, preventing a detailed analysis over a large number
of potential nanostructures and limiting the analysis to systems with
a few 100s of atoms. Recent advances in machine learned interatomic
potentials suggest that dynamics can be accelerated with surrogate
models which replace the full solution of the Schrödinger Equation.
Here, we modify an existing neural network, Hierarchically Interacting
Particle Neural Network (HIP-NN), to predict plasmon dynamics in Ag
nanoparticles. The model takes as a minimum as three time steps of
the reference real-time time-dependent density functional theory (rt-TDDFT)
calculated charges as history and predicts trajectories for 5 fs in
great agreement with the reference simulation. Further, we show that
a multistep training approach in which the loss function includes
errors from future time-step predictions can stabilize the model predictions
for the entire simulated trajectory (∼25 fs). This extends
the model’s capability to accurately predict plasmon dynamics
in large nanoparticles of up to 561 atoms, not present in the training
data set. More importantly, with machine learning models on GPUs,
we gain a speed-up factor of ∼103 as compared with
the rt-TDDFT calculations when predicting important physical quantities
such as dynamic dipole moments in Ag55 and a factor of
∼104 for extended nanoparticles that are 10 times
larger. This underscores the promise of future machine learning accelerated
electron/nuclear dynamics simulations for understanding fundamental
properties of plasmon-driven hot carrier devices.