Atomistic simulations utilising short ranged interatomic force fields can be parallelized in space but not in time, limiting trajectory timescales to microseconds irrespective of the number of available processors. As material evolution is routinely controlled by rare events over the timescales of milliseconds to years it is therefore essential to coarse grain atomistic simulations into mesoscale models to allow access to the time and length scales of significance for materials science. Error in this process arises from two main sources.
First, a priori or intuition based coarse graining can have potentially disastrous assumptions on the possible underlying atomistic processes. As a result, the produced mesoscale model is fundamentally unable to capture the behaviour of the true atomistic system, meaning a more agnostic approach must be developed.
Second, implicit electron force fields are always models of the Hellman-Feynman forces driving Born-Oppenheimer dynamics. Whilst traditional empirical forms are able to accurately capture certain regions of a material's energy landscape, force field development is being revolutionised by the non-linear regression techniques of machine learning, which are increasingly capable of ab initio accuracy. Nevertheless, such accuracy can only be achieved if the training database of configurations to which the regression is applied is sufficiently diverse and relevant for the problem under study.
To solve these problems at the petascale and exascale, autonomous uncertainty quantification is of central importance. This research program will develop Bayesian estimators of atomistic sampling completeness to optimize the automated, massively parallel construction of mesoscale models. The discovered mechanisms and uncertainty quantifiers will also be used to improve force field parametrization in kinetically important regions of configuration space. The goal is an exascale-efficient, autonomous, uncertainty-aware coarse graining scheme that allows quantitative insight into complex mechanisms of material evolution.
Monsieur Thomas SWINBURNE (CENTRE NATIONAL DE LA RECHERCHE SCIENTIFIQUE DELEGATION PROVENCE ET CORSE CENTRE INTERDISCIPLINAIRE DE NANOSCIENCE DE MARSEILLE)
The author of this summary is the project coordinator, who is responsible for the content of this summary. The ANR declines any responsibility as for its contents.
CINaM CENTRE NATIONAL DE LA RECHERCHE SCIENTIFIQUE DELEGATION PROVENCE ET CORSE CENTRE INTERDISCIPLINAIRE DE NANOSCIENCE DE MARSEILLE
CEA / Service de Recherche en Métallurgie Physique
Physics and Chemistry of Materials (Theoretical Division) / Los Alamos National Laboratory
Theory and simulation of materials / Culham Centre for Fusion Energy
Help of the ANR 200,448 euros
Beginning and duration of the scientific project: February 2020 - 30 Months