Neural networks and interfaces: theoretical considerations and practical solutions

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• Samuel Niblett, Lawrence Berkeley National Laboratory
• Monday 06 December 2021, 16:00-16:30
• BMS Lecture Theatre, Department of Chemistry.

If you have a question about this talk, please contact Dr Christoph Schran.

This talk will be in hybrid format. Virtual access via: https://zoom.us/j/92447982065?pwd=RkhaYkM5VTZPZ3pYSHptUXlRSkppQT09

Reactive machine-learned potentials have recently emerged as one of the most promising computational tools for materials chemistry, allowing us to apply statistical mechanical methods to more realistic and complex problems than ever before. Many of these problems require training models of exotic environments and non-equilibrium boundary conditions, where existing model architectures and training protocols may not be suitable. These limitations are only now beginning to be explored.

In this talk, I will show that the inherent localisation of most symmetry functions prevents standard machine-learned models from describing liquid-vapour interfaces correctly, since many properties of these interfaces are sensitive to unbalanced long-range forces such as electrostatic interactions. Using the perspective of local molecular field (LMF) theory due to Weeks and coworkers, I will show how neural network potentials attempt to represent these long-ranged forces and where they fail. The LMF approach suggests a simple modification to the neural network method that dramatically improves the description of polarisation-dependent properties. I will also discuss practical details of our neural network protocols, including refinements to the standard loss functions and our approach to data generation, both of which improve training efficiency and model generalisation.

This talk is part of the Lennard-Jones Centre series.

This talk is included in these lists:

• BMS Lecture Theatre, Department of Chemistry
• Hanchen DaDaDash
• Lennard-Jones Centre

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