pGM5P-26: A Polarizable Gaussian Multipole Water Model with Transferable Temperature-Dependent Thermodynamics.
- 1Department of Chemical and Biomolecular Engineering, Molecular Biology and Biochemistry, Materials Science and Engineering, and Biomedical Engineering, University of California, Irvine, California92697, United States.
- 2SBP Medical Discovery Institute , 10901 North Torrey Pines Road, La Jolla, California92037, United States.
- 3UC Davis Genome Center and Department of Biomedical Engineering, University of California, Davis, One Shields Avenue, Davis, California95616, United States.
Abstract
Water belongs to a small family of liquids whose density maximum lies above the melting point, a signature of their preference for open, tetrahedral networks. Reproducing this anomalous density-temperature curve, together with ambient thermodynamics, remains a demanding test for water force fields: fixed-charge models trade 298 K accuracy for large errors in ρ(T), while point-multipole polarizable models must exclude the 1-2 and 1-3 intramolecular contributions that govern molecular anisotropy and, through nonadditive coupling, shape the long-range field. We present pGM5P-26, a five-point polarizable Gaussian Multipole (pGM) water model whose Gaussian-distributed charges and dipoles remain finite at all distances, giving a unified treatment of short- and long-range electrostatics that retains these intramolecular contributions in a fully self-consistent induction. Its 14 independent parameters were optimized exclusively at 298 K against the liquid density, oxygen-oxygen radial distribution function, and uncorrected finite-box self-diffusion coefficient using SMAC Bayesian optimization with Hyperband scheduling. Despite this single-temperature training, pGM5P-26 gives the lowest absolute density RMSE and the second-lowest 298 K-anchored density-shape RMSE among the ten simulated models over the out-of-training temperatures from 245 to 380 K. Its thermal-expansion curve ranks second by both metrics, and its approximate finite-size-corrected self-diffusion curve ranks third, placing all three temperature dependences among the closest to experiment in the benchmark set. Its temperature of maximum density is 280.3 K (experiment: 277.1 K), the second closest after TIP4P/2005. The second virial coefficient reaches near-quantitative agreement with experiment above 773 K. These results show that Gaussian multipole polarization combined with automated optimization captures water's density anomaly without explicit temperature-dependent training.
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BibTeX
@article{wu2026pgm5p26,
title = {{pGM5P-26: A Polarizable Gaussian Multipole Water Model with Transferable Temperature-Dependent Thermodynamics.}},
author = {Yongxian Wu and Piotr Cieplak and Yong Duan and Ray Luo},
journal = {Journal of chemical theory and computation},
year = {2026},
month = oct,
doi = {10.1021/acs.jctc.6c01267},
url = {https://europepmc.org/article/MED/42917296},
note = {CC BY-NC-ND},
}
RIS
TY - JOUR
TI - pGM5P-26: A Polarizable Gaussian Multipole Water Model with Transferable Temperature-Dependent Thermodynamics.
AU - Yongxian Wu
AU - Piotr Cieplak
AU - Yong Duan
AU - Ray Luo
PY - 2026
DA - 2026/10/01
JO - Journal of chemical theory and computation
DO - 10.1021/acs.jctc.6c01267
UR - https://europepmc.org/article/MED/42917296
AB - Water belongs to a small family of liquids whose density maximum lies above the melting point, a signature of their preference for open, tetrahedral networks. Reproducing this anomalous density-temperature curve, together with ambient thermodynamics, remains a demanding test for water force fields: fixed-charge models trade 298 K accuracy for large errors in ρ(T), while point-multipole polarizable models must exclude the 1-2 and 1-3 intramolecular contributions that govern molecular anisotropy and, through nonadditive coupling, shape the long-range field. We present pGM5P-26, a five-point polarizable Gaussian Multipole (pGM) water model whose Gaussian-distributed charges and dipoles remain finite at all distances, giving a unified treatment of short- and long-range electrostatics that retains these intramolecular contributions in a fully self-consistent induction. Its 14 independent parameters were optimized exclusively at 298 K against the liquid density, oxygen-oxygen radial distribution function, and uncorrected finite-box self-diffusion coefficient using SMAC Bayesian optimization with Hyperband scheduling. Despite this single-temperature training, pGM5P-26 gives the lowest absolute density RMSE and the second-lowest 298 K-anchored density-shape RMSE among the ten simulated models over the out-of-training temperatures from 245 to 380 K. Its thermal-expansion curve ranks second by both metrics, and its approximate finite-size-corrected self-diffusion curve ranks third, placing all three temperature dependences among the closest to experiment in the benchmark set. Its temperature of maximum density is 280.3 K (experiment: 277.1 K), the second closest after TIP4P/2005. The second virial coefficient reaches near-quantitative agreement with experiment above 773 K. These results show that Gaussian multipole polarization combined with automated optimization captures water's density anomaly without explicit temperature-dependent training.
SN - 1549-9618
SN - 1549-9626
ER -