Charge-overlap model of physical interactions and a combining rule for unlike systems

Short-range repulsion within intermolecular force fields is conventionally described by either Lennard-Jones (A/r(12)) or Born-Mayer (A exp(-Br)) forms. Despite their widespread use, these simple functional forms are often unable to describe the interaction energy accurately over a broad range of intermolecular distances, thus creating challenges in the development of ab initio force fields and potentially leading to decreased accuracy and transferability. Herein, we derive a novel short-range functional form based on a simple Slater-like model of overlapping atomic densities and an iterated stockholder atom (ISA) partitioning of the molecular electron density. We demonstrate that this Slater-ISA methodology yields a more accurate, transferable, and robust description of the short-range interactions at minimal additional computational cost compared to standard Lennard-Jones or Born-Mayer approaches. Finally, we show how this methodology can be adapted to yield the standard Born-Mayer functional form while still retaining many of the advantages of the Slater-ISA approach.

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“…Following literature precedent, 40,59 we hypothesized that ξ could be treated as a universal constant.…”

Section: Next-generation Born-mayer Models: Born-mayer-sisa Ffmentioning

confidence: 99%

“…38,[51][52][53] The exponential term dominates the asymptotic form of the density, and the r-dependent prefactor may be neglected. 11,39,40,54 In this case, the density takes the even simpler form…”

Section: Models For the Exchange-repulsion Between Isolated Atomsmentioning

confidence: 99%

Beyond Born–Mayer: Improved Models for Short-Range Repulsion in ab Initio Force Fields

Vleet

Misquitta

Stone

et al. 2016

J. Chem. Theory Comput.

109

160

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“…[80][81][82][83][84][85][86][87][88] The last choice is irrelevant when computing single-ion solvation properties, but becomes crucial when extending the application range to ionic solutions, [89][90][91][92][93][94][95][96][97][98][99][100][101][102][103][104][105][106][107] liquids, 108-117 melts 89, 118-137 or crystals. 101,104,[137][138][139][140][141][142][143] Given the above four choices, the calculated (corrected) ionic sol-vation free energies are exclusively determined by the set of ion-solvent van der Waals (e.g., Lennard-Jones) interaction parameters employed in the simulation.…”

Section: Introductionmentioning

confidence: 99%

Computation of methodology-independent single-ion solvation properties from molecular simulations. IV. Optimized Lennard-Jones interaction parameter sets for the alkali and halide ions in water

Reif

Hünenberger

2011

The Journal of Chemical Physics

143

238

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The raw single-ion solvation free energies computed from atomistic (explicit-solvent) simulations are extremely sensitive to the boundary conditions and treatment of electrostatic interactions used during these simulations. However, as shown recently [M. A. Kastenholz and P. H. Hünenberger, J. Chem. Phys. 124, 224501 (2006); M. M. Reif and P. H. Hünenberger, J. Chem. Phys. 134, 144103 (2010)], the application of appropriate correction terms permits to obtain methodology-independent results. The corrected values are then exclusively characteristic of the underlying molecular model including in particular the ion-solvent van der Waals interaction parameters, determining the effective ion size and the magnitude of its dispersion interactions. In the present study, the comparison of calculated (corrected) hydration free energies with experimental data (along with the consideration of ionic polarizabilities) is used to calibrate new sets of ion-solvent van der Waals (Lennard-Jones) interaction parameters for the alkali (Li(+), Na(+), K(+), Rb(+), Cs(+)) and halide (F(-), Cl(-), Br(-), I(-)) ions along with either the SPC or the SPC/E water models. The experimental dataset is defined by conventional single-ion hydration free energies [Tissandier et al., J. Phys. Chem. A 102, 7787 (1998); Fawcett, J. Phys. Chem. B 103, 11181] along with three plausible choices for the (experimentally elusive) value of the absolute (intrinsic) hydration free energy of the proton, namely, ΔG(hyd)(⊖)[H(+)] = -1100, -1075 or -1050 kJ mol(-1), resulting in three sets L, M, and H for the SPC water model and three sets L(E), M(E), and H(E) for the SPC/E water model (alternative sets can easily be interpolated to intermediate ΔG(hyd)(⊖)[H(+)] values). The residual sensitivity of the calculated (corrected) hydration free energies on the volume-pressure boundary conditions and on the effective ionic radius entering into the calculation of the correction terms is also evaluated and found to be very limited. Ultimately, it is expected that comparison with other experimental ionic properties (e.g., derivative single-ion solvation properties, as well as data concerning ionic crystals, melts, solutions at finite concentrations, or nonaqueous solutions) will permit to validate one specific set and thus, the associated ΔG(hyd)(⊖)[H(+)] value (atomistic consistency assumption). Preliminary results (first-peak positions in the ion-water radial distribution functions, partial molar volumes of ionic salts in water, and structural properties of ionic crystals) support a value of ΔG(hyd)(⊖)[H(+)] close to -1100 kJ·mol(-1).

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“…We assume that the adsorption potential can be derived from a sum of Lennard-Jones (LJ) two-body interactions between the host C atoms and the adsorbate. This pair potential has distance and energy parameters obtained with semiempirical combining rules from the LJ ǫ and σ parameters of the C atoms and the adsorbate [24][25][26][27]:…”

Section: Introductionmentioning

confidence: 99%

Uptake of gases in bundles of carbon nanotubes

et al. 2000

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Model calculations are presented which predict whether or not an arbitrary gas experiences significant absorption within carbon nanotubes and/or bundles of nanotubes. The potentials used in these calculations assume a conventional form, based on a sum of two-body interactions with individual carbon atoms; the latter employ energy and distance parameters which are derived from empirical combining rules. The results confirm intuitive expectation that small atoms and molecules are absorbed within both the interstitial channels and the tubes, while large atoms and molecules are absorbed almost exclusively within the tubes.Comment: 9 pages, 12 figures, submitted to PRB Newer version (8MAR2K). There was an error in the old one (23JAN2K). Please download thi

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Charge-overlap model of physical interactions and a combining rule for unlike systems

Cited by 23 publications

References 45 publications

Beyond Born–Mayer: Improved Models for Short-Range Repulsion in ab Initio Force Fields

Beyond Born–Mayer: Improved Models for Short-Range Repulsion in ab Initio Force Fields

Computation of methodology-independent single-ion solvation properties from molecular simulations. IV. Optimized Lennard-Jones interaction parameter sets for the alkali and halide ions in water

Uptake of gases in bundles of carbon nanotubes

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