Toward a Universal Water Model: First Principles Simulations from the Dimer to the Liquid Phase

Abstract

A full-dimensional model of water, HBB2-pol, derived entirely from "first-principles", is introduced and employed in computer simulations ranging from the dimer to the liquid. HBB2-pol provides excellent agreement with the measured second and third virial coefficients and, by construction, reproduces the dimer vibration-rotation-tunneling spectrum. The model also predicts the relative energy differences between isomers of small water clusters within the accuracy of highly correlated electronic structure methods. Importantly, when combined with simulation methods that explicitly include zero-point energy and quantum thermal motion, HBB2-pol accurately describes both structural and dynamical properties of the liquid phase.

The Carbon-Water Interface: Modeling Challenges and Opportunities for the Water-Energy Nexus

“…Most simulations discussed so far have been performed with empirical potentials (i.e., classical force fields), which are sensitive to the choice of the potentials used. Many classical models are available for the description of water--water interactions (135,136), and some have been used to investigate interfacial systems (107).…”

Concerted hydrogen-bond breaking by quantum tunneling in the water hexamer prism

“…The cluster dynamics can be probed by high-resolution rovibrational spectroscopy (1)(2)(3)(4)(5)(6)(7)(8)(9) and interpreted by theoretical simulations (10)(11)(12)(13)(14)(15)(16)(17)(18)(19)(20)(21)(22)(23)(24)(25)(26)(27). The nature of the interactions between the water molecules is the same in the clusters as in the bulk (many-body forces beyond the three-body term are relatively weak) (28), and hence the cluster spectra can be used to test universal models (25,(29)(30)(31)(32) of the water intermolecular potential energy surface, giving insight into hydrogen bonding in all phases of water. At low temperatures, the molecules are frozen into a network and can only rearrange by quantum tunneling, which causes splittings in the spectrum ranging from MHz to THz (33).…”

Communication: Energy benchmarking with quantum Monte Carlo for water nano-droplets and bulk liquid water

“…The importance of B2B energy is clear from the fact that the dipole moment of the H 2 O monomer increases greatly (from 1.86 D to ∼2.6 D) on going from the gas phase to condensed phases, 30,31 so that the interaction between a pair of molecules is strongly affected by the presence of other molecules. B2B errors can be an important cause of inaccuracies in DFT, 5,32,33 but their effect is likely to become fully apparent only for rather large H 2 O aggregates, and this is why accurate benchmarks for such aggregates are essential. 34 There is now abundant evidence that the diffusion Monte Carlo (DMC) form of QMC approaches coupled-cluster accuracy for water systems.…”

“…Very recent work on large configuration samples of the water trimer shows that the BLYP 3-body energy systematically overbinds, 33 and it is natural to ask whether the B2B overbinding in the nano-droplets can be attributed to 3-body effects. To answer this, we constructed an approximate algorithm to represent short-range 3-body errors, following the methods of Paesani and co-workers, 5,33 parameterizing it by least-squares fitting to data for a large thermal sample of trimer configurations (see the supplementary material 15 ). Correction of BLYP-2 using this algorithm leaves only very small errors (deviations from DMC), as shown in Fig.…”