Scaling Out Transformer Models for Retrosynthesis on Supercomputers.

Retrosynthesis is the task of building a molecule from smaller precursor molecules. As shown in previous work, good results can be achieved on this task with the help of deep learning techniques, for ex- ample with the help of Transformer networks. Here the retrosynthesis task is treated as a machine translation problem where the Transformer network predicts the precursor molecules given a string representation of the target molecule. Previous research has focused on performing the training procedure on a single machine but in this article we investigate the effect of scaling the training of the Transformer networks for the retrosynthesis task on supercomputers. We investigate the issues that arise when scaling Transformers to multiple machines such as learning rate scheduling and choice of optimizer, and present strategies that improve results compared to previous research. By training on multiple machines we are able to increase the top-1 accuracy by 2.5% to 43.6%. In an attempt to improve results further, we experiment with increasing the number of parameters in the Transformer network but find that models are prone to overfitting, which can be attributed to the small dataset used for training the models. On these runs we manage to achieve a scaling efficiency of nearly 70%