PANNA is a package for training and validating neural networks to represent atomic potentials. It implements configurable all-to-all connected deep neural network architectures which allow for the exploration of training dynamics. Currently it includes tools to enable original[1] and modified[2] Behler-Parrinello input feature vectors, both for molecules and crystals, but the network can also be used in an input-agnostic fashion to enable further experimentation. PANNA is written in Python and relies on TensorFlow as underlying engine.
A common way to use PANNA in its current implementation is to train a neural network in order to estimate the total energy of a molecule or crystal, as a sum of atomic contributions, by learning from the data of reference total energy calculations for similar structures (usually ab-initio calculations).
The neural network models in literature often start from a description of the system of interest in terms of local feature vectors for each atom in the configuration. PANNA provides tools to calculate two versions of the Behler-Parrinello local descriptors but it allows the use of any species-resolved, fixed-size array that describes the input data.
PANNA allows the construction of neural network architectures with different sizes for each of the atomic species in the training set. Currently the allowed architecture is a deep neural network of fully connected layers, starting from the input feature vector and going through one or more hidden layers. The user can determine to train or freeze any layer, s/he can also transfer network parameters between species upon restart.
In summary, PANNA is an easy-to-use interface for obtaining neural network models for atomistic potentials, leveraging the highly optimized TensorFlow infrastructure to provide an efficient and parallelized, GPU-accelerated training.
It provides:
- an input creation tool (atomistic calculation result -> G-vector )
- an input packaging tool for quick processing of TensorFlow ( G-vector -> TFData bundle)
- a network training tool
- a network validation tool
- a LAMMPS plugin
- a bundle of sample data for testing[3]
See the full documentation of PANNA at https://gitlab.com/PANNAdevs/panna/blob/master/doc/PANNA_documentation.md
GitLab repository for PANNA: https://gitlab.com/PANNAdevs/panna
See manuscript at https://arxiv.org/abs/1907.03055
