Data-Driven Many-Body Models with Chemical Accuracy for CH4/H2O Mixtures

Abstract

<div> <div> <div> <p>Many-body potential energy functions (PEFs) based on the TTM-nrg and MB-nrg theoretical/computational frameworks are developed from coupled cluster reference data for neat methane and mixed methane/water systems. It is shown that that the MB-nrg PEFs achieve subchemical accuracy in the representation of individual many-body effects in small clusters and enables predictive simulations from the gas to the liquid phase. Analysis of structural properties calculated from molecular dynamics simulations of liquid methane and methane/water mixtures using both TTM-nrg and MB-nrg PEFs indicates that, while accounting for polarization effects is important for a correct description of many-body interactions in the liquid phase, an accurate representation of short-range interactions, as provided by the MB-nrg PEFs, is necessary for a quantitative description of the local solvation structure in liquid mixtures. </p> </div> </div> </div>

MB-Fit: Software Infrastructure for Data-Driven Many-Body Potential Energy Functions

“…The first source was normal-mode sampling of the NH 3 -NH 3 optimized dimer which was carried out adopting the same protocol described above for the 1B sets. The second source was scans along the N-N distance of the NH 3 -NH 3 dimer with rigid NH 3 which, as previously found for other molecular systems, 97,98 demonstrate that the MB-nrg PEFs are able to quantitatively reproduce QM reference data, independently of the QM level of theory.…”

“…As shown in previous studies, 92,95,[97][98][99] higher accuracy in modeling 2B energies is achieved by the MB-nrg PEFs that adopt short-range PIPs to effectively represent 2B quantum-mechanical in- teractions that arise from the overlap of the monomers' electron densities (e.g., Pauli repulsion, and charge transfer and penetration). 58,59,61,92,95,97,98,103,105,139 The 2B training (7261 configurations) and test (1449 configurations) sets for the MB-nrg PEFs were generated by including configurations extracted from three different sources. The first source was normal-mode sampling of the NH 3 -NH 3 optimized dimer which was carried out adopting the same protocol described above for the 1B sets.…”

“…1 served as a rigorous theoretical framework for the development of TTM-nrg and MB-nrg PEFs for various aqueous systems and molecular fluids, which are fully transferable from the gas to the condensed phase. Specifically, building upon the MB-pol PEF for water, TTM-nrg and MB-nrg PEFs were introduced for halide 91,92 and alkali-metal ions 94,95 in water, water-carbon dioxide 97 and water-methane 98 mixtures, and small molecules in water. 99 When used in computer simulations, the TTM-nrg and MB-nrg PEFs consistently provide remarkable agreement with experimental data, which is effectively quantitative in the case of the MB-nrg PEFs.…”

“…99 When used in computer simulations, the TTM-nrg and MB-nrg PEFs consistently provide remarkable agreement with experimental data, which is effectively quantitative in the case of the MB-nrg PEFs. 97,98,[100][101][102][103][104][105]107 In the most general form, the TTM-nrg and MB-nrg PEFs approximate the MBE of Eq. 1 as…”

“…[58][59][60] MB-pol has been shown to correctly reproduce the properties of water, 56,61 from small gas-phase clusters [62][63][64][65][66][67][68][69][70][71][72][73] to liquid water, [74][75][76][77][78][79][80] the air/water interface, [81][82][83][84][85] , and ice. [86][87][88][89][90] The hybrid data-driven/physics-based scheme originally developed for MB-pol was later extended to generic molecules through the introduction of two families of MB-PEFs, the TTM-nrg (for "Thole-type model energy") and MB-nrg (for "many-body energy") PEFs, for halide [91][92][93] and alkali-metal [94][95][96] ions in water, molecular fluids, 97,98 and small molecules in water. 99 When employed in computer simulations, the MB-nrg PEFs have been shown to consistently provide remarkable agreement with experimental data for both gas-phase and condensed-phase systems.…”