Real-space mutual information (RSMI) was shown to be an important quantity, formally and from a numerical standpoint, in finding coarse-grained descriptions of physical systems. It very generally quantifies spatial correlations and can give rise to constructive algorithms extracting relevant degrees of freedom. Efficient and reliable estimation or maximization of RSMI is, however, numerically challenging. A recent breakthrough in theoretical machine learning has been the introduction of variational lower bounds for mutual information, parametrized by neural networks. Here we describe in detail how these results can be combined with differentiable coarse-graining operations to develop a single unsupervised neural-network-based algorithm, the RSMI-NE, efficiently extracting the relevant degrees of freedom in the form of the operators of effective field theories, directly from real-space configurations. We study the information contained in the statistical ensemble of constructed coarse-graining transformations and its recovery from partial input data using a secondary machine learning analysis applied to this ensemble. In particular, we show how symmetries, also emergent, can be identified. We demonstrate the extraction of the phase diagram and the order parameters for equilibrium systems and consider also an example of a nonequilibrium problem.
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http://dx.doi.org/10.1103/PhysRevE.104.064106 | DOI Listing |
J Chem Phys
March 2024
CAMD, Department of Physics, Technical University of Denmark, 2800 Kgs. Lyngby, Denmark.
Adv Mater
January 2024
Diamond Light Source, Harwell Campus, Didcot, Oxfordshire, OX11 0DE, UK.
The omnipresence of charge density waves (CDWs) across almost all cuprate families underpins a common organizing principle. However, a longstanding debate of whether its spatial symmetry is stripe or checkerboard remains unresolved. While CDWs in lanthanum- and yttrium-based cuprates possess a stripe symmetry, distinguishing these two scenarios is challenging for the short-range CDW in bismuth-based cuprates.
View Article and Find Full Text PDFJ Phys Chem A
July 2023
Institute of Functional Nano & Soft Materials (FUNSOM), Jiangsu Key Laboratory for Carbon-Based Functional Materials & Devices, Soochow University, Suzhou, Jiangsu 215123, China.
Since the structures of crystals/molecules are often non-Euclidean data in real space, graph neural networks (GNNs) are regarded as the most prospective approach for their capacity to represent materials by graph-based inputs and have emerged as an efficient and powerful tool in accelerating the discovery of new materials. Here, we propose a self-learning-input GNN framework, named self-learning-input GNN (SLI-GNN), to uniformly predict the properties for both crystals and molecules, in which we design a dynamic embedding layer to self-update the input features along with the iteration of the neural network and introduce the Infomax mechanism to maximize the average mutual information between the local features and the global features. Our SLI-GNN can reach ideal prediction accuracy with fewer inputs and more message passing neural network (MPNN) layers.
View Article and Find Full Text PDFJ Am Chem Soc
November 2022
Department of Applied Physics, Aalto University, 00076 Aalto, Espoo, Finland.
The existence of water dimers in equilibrium water vapor at room temperature and their anomalous properties revealed by recent studies suggest the benchmark role of water dimers in both experiment and theory. However, there has been a limited observation of individual water dimers due to the challenge of water separation and generation at the single-molecule level. Here, we achieve real-space imaging of individual confined water dimers embedded inside a self-assembled layer of a DNA base, adenine, on Ag(111).
View Article and Find Full Text PDFMolecules
September 2022
Department of Analytical and Physical Chemistry, University of Oviedo, 33006 Oviedo, Spain.
The somewhat elusive concept of aromaticity plays an undeniable role in the chemical narrative, often being considered the principal cause of the unusual properties and stability exhibited by certain π skeletons. More recently, the concept of aromaticity has also been utilised to explain the modulation of the strength of non-covalent interactions (NCIs), such as hydrogen bonding (HB), paving the way towards the in silico prediction and design of tailor-made interacting systems. In this work, we try to shed light on this area by exploiting real space techniques, such as the Quantum Theory of Atoms in Molecules (QTAIM), the Interacting Quantum Atoms (IQA) approaches along with the electron delocalisation indicators Aromatic Fluctuation (FLU) and Multicenter (MCI) indices.
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