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Heat transport in liquid water from first-principles and deep neural network simulations

Author(s): Tisi, Davide; Zhang, Linfeng; Bertossa, Riccardo; Wang, Han; Car, Roberto; et al

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Abstract: We compute the thermal conductivity of water within linear response theory from equilibrium molecular dynamics simulations, by adopting two different approaches. In one, the potential energy surface (PES) is derived on the fly from the electronic ground state of density functional theory (DFT) and the corresponding analytical expression is used for the energy flux. In the other, the PES is represented by a deep neural network (DNN) trained on DFT data, whereby the PES has an explicit local decomposition and the energy flux takes a particularly simple expression. By virtue of a gauge invariance principle, established by Marcolongo, Umari, and Baroni, the two approaches should be equivalent if the PES were reproduced accurately by the DNN model. We test this hypothesis by calculating the thermal conductivity, at the GGA (PBE) level of theory, using the direct formulation and its DNN proxy, finding that both approaches yield the same conductivity, in excess of the experimental value by approximately 60%. Besides being numerically much more efficient than its direct DFT counterpart, the DNN scheme has the advantage of being easily applicable to more sophisticated DFT approximations, such as meta-GGA and hybrid functionals, for which it would be hard to derive analytically the expression of the energy flux. We find in this way that a DNN model, trained on meta-GGA (SCAN) data, reduces the deviation from experiment of the predicted thermal conductivity by about 50%, leaving the question open as to whether the residual error is due to deficiencies of the functional, to a neglect of nuclear quantum effects in the atomic dynamics, or, likely, to a combination of the two.
Publication Date: 13-Dec-2021
Electronic Publication Date: 13-Dec-2021
Citation: Tisi, Davide, Zhang, Linfeng, Bertossa, Riccardo, Wang, Han, Car, Roberto, Baroni, Stefano. (Heat transport in liquid water from first-principles and deep neural network simulations. Physical Review B, 104 (22), 10.1103/physrevb.104.224202
DOI: doi:10.1103/physrevb.104.224202
ISSN: 2469-9950
EISSN: 2469-9969
Language: en
Type of Material: Journal Article
Journal/Proceeding Title: Physical Review B
Version: Author's manuscript

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