FisMat2017 - Submission - View

Abstract's title: Accelerating Crystal Structure Prediction with Deep Neural Networks
Submitting author: Ruggero Lot
Affiliation: Università degli studi di Trieste (UNITS)
Affiliation Address: Piazzale Europa, 1 34127 Trieste
Country: Italy
Oral presentation/Poster (Author's request): Poster
Other authors and affiliations: Emine Kucukbenli (SISSA), Stefano de Gironcoli (SISSA)

Ab initio crystal structure prediction is well known to have high computational cost resulting from the exploration of a huge phase space with many degrees of freedom. Despite intelligent strategies implemented for the search[1], much of the time is still spent in performing ab-initio calculations in regions of the phase space far from the global minimum.
In this work we propose a new strategy based on ab-initio quality energetics obtained from deep neural-networks as implemented in the TensorFlow library[2] to increase the efficiency of the search and demonstrate its effectiveness in the example of Glycine molecular crystals. We start with modified Behler-Parrinello symmetry functions[3] to build single-atom environment vectors to represent the crystal structure. We train a layered, all-to-all connected network for each atomic type on a database of ab-initio calculations. The total energy is expressed as a sum of individual, environment dependent, atomic contributions[4]. We explore the machine learning performance of such a network not only for energies but also for forces and pressure with respect to training data, network architecture and training process. We then show the harmonious integration of this strategy into the existing crystal structure prediction workflow and test its applicability to system sizes that could not be tackled otherwise. References:[1] Lyakhov A.O., Oganov A.R., Stokes H.T., Zhu Q. (2013). Comp. Phys. Comm. 184, 1172-1182 [2] [3] J.Behler and M. Parrinello (2007). Phys.Rev.Lett. 98, 146401 [4] J. S. Smith, O. Isayev, A. E. Roitberg, (2017), Chem. Sci., 8, 3192-3203