Prediction of conformationally dependent atomic multipole moments in carbohydrates. Issue 32 (8th November 2015)

• Record Type: Journal Article
• Authors: Cardamone, Salvatore; Popelier, Paul L. A.
• Is Part Of: Journal of computational chemistry. Volume 36:Issue 32(2015)
• Page Start: 2361
• Page End: 2373
• Publication Date: 2015-11-08
• Subjects: quantum theory of atoms in molecules -- carbohydrates -- quantum chemical topology -- conformational sampling -- kriging -- electrostatics -- multipole moments; Chemistry -- Data processing -- Periodicals; 542.85
• DOI: 10.1002/jcc.24215
• Languages: English
• ISSNs: 0192-8651

Abstract

Abstract : The conformational flexibility of carbohydrates is challenging within the field of computational chemistry. This flexibility causes the electron density to change, which leads to fluctuating atomic multipole moments. Quantum Chemical Topology (QCT) allows for the partitioning of an "atom in a molecule, " thus localizing electron density to finite atomic domains, which permits the unambiguous evaluation of atomic multipole moments. By selecting an ensemble of physically realistic conformers of a chemical system, one evaluates the various multipole moments at defined points in configuration space. The subsequent implementation of the machine learning method kriging delivers the evaluation of an analytical function, which smoothly interpolates between these points. This allows for the prediction of atomic multipole moments at new points in conformational space, not trained for but within prediction range. In this work, we demonstrate that the carbohydrates erythrose and threose are amenable to the above methodology. We investigate how kriging models respond when the training ensemble incorporating multiple energy minima and their environment in conformational space. Additionally, we evaluate the gains in predictive capacity of our models as the size of the training ensemble increases. We believe this approach to be entirely novel within the field of carbohydrates. For a modest training set size of 600, more than 90% of the external test configurations have an error in the total (predicted) electrostatic energy (relative to ab initio ) of maximum 1 kJ mol −1 for open chains and just over 90% an error of maximum 4 kJ mol −1 for rings. © 2015 Wiley Periodicals, Inc. Abstract : This work demonstrates proof‐of‐concept for a next‐generation carbohydrate force field. The method proposes high‐rank multipolar electrostatics, each multipole moment matched with its own polarization. The latter is achieved by the machine learning technique called Kriging (aka Gaussian Processes). For a training set size of 600, more than 90% of the external test configurations have an error in the total (predicted) electrostatic energy (relative to ab initio ) of maximum 1 kJ mol −1 for open chains.