The four-body nonadditive contribution to the energy of four helium atoms is calculated and fitted for all geometries for which the internuclear distances exceed a small minimum value. The interpolation uses an active learning approach based on Gaussian processes. Asymptotic functions are used to calculate the nonadditive energy when the four helium atoms form distinct subclusters. The resulting four-body potential is used to compute the fourth virial coefficient () for helium, at temperatures from 10 to 2000 K, with a path-integral approach that fully accounts for quantum effects. The results are in reasonable agreement with the limited and scattered experimental data for (), but our calculated results have much smaller uncertainties.
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http://dx.doi.org/10.1021/acs.jced.3c00578 | DOI Listing |
J Chem Eng Data
December 2023
Applied Chemicals and Materials Division, National Institute of Standards and Technology, Boulder, Colorado 80305-3337, United States.
The four-body nonadditive contribution to the energy of four helium atoms is calculated and fitted for all geometries for which the internuclear distances exceed a small minimum value. The interpolation uses an active learning approach based on Gaussian processes. Asymptotic functions are used to calculate the nonadditive energy when the four helium atoms form distinct subclusters.
View Article and Find Full Text PDFJ Chem Theory Comput
February 2021
Department of Chemical Physics and Optics, Faculty of Mathematics and Physics, Charles University, Ke Karlovu 3, CZ-12116 Prague 2, Czech Republic.
The many-body expansion (MBE) of energies of molecular clusters or solids offers a way to detect and analyze errors of theoretical methods that could go unnoticed if only the total energy of the system was considered. In this regard, the interaction between the methane molecule and its enclosing dodecahedral water cage, CH···(HO), is a stringent test for approximate methods, including density functional theory (DFT) approximations. Hybrid and semilocal DFT approximations behave erratically for this system, with three- and four-body nonadditive terms having neither the correct sign nor magnitude.
View Article and Find Full Text PDFJ Phys Chem A
November 2019
Research Computing Center , University of North Carolina, Chapel Hill , North Carolina 27599-3420 , United States.
High-spin lithium clusters, Li ( = 2-21), have been systematically studied by using density functional theory. Although these high-spin clusters have no bonding electron pairs, they are stable with respect to isolated atoms. A set of 42 density functional theory functionals were benchmarked against CCSD(T)/cc-pVQZ results for clusters from the dimer to the hexamer.
View Article and Find Full Text PDFJ Chem Phys
June 2015
CNR-IPCF, Viale F. Stagno d'Alcontres, 37-98158 Messina, Italy.
The relevance of neglecting three- and four-body interactions in the coarse-grained version of the Asakura-Oosawa model is examined. A mapping between the first few virial coefficients of the binary nonadditive hard-sphere mixture representative of this model and those arising from the coarse-grained (pairwise) depletion potential approximation allows for a quantitative evaluation of the effect of such interactions. This turns out to be especially important for large size ratios and large reservoir polymer packing fractions.
View Article and Find Full Text PDFJ Phys Chem A
June 2011
IQTCUB, Departament de Química Física, Universitat de Barcelona, Barcelona, Spain.
The semiempirical methodology, introduced to describe noncovalent intermolecular interactions in atom/ion-molecule systems, is here extended to investigate a prototype cluster, formed by benzene (Bz) and closed-shell ions (Na(+) and/or Cl(-)), surrounded by neutral species (Ar), forming solvation shells. The involved multidimensional potential energy surface (PES) is assumed to depend on a critical balancing of some effective interaction components. In particular, for the Ar solvated Bz-Na(+)-Cl(-) system, the nonelectrostatic component of the total interaction has been formulated as a combination of two-, three-, and four-body contributions, each one represented by a proper function, with the four-body and part of the three-body terms arising from nonadditive induction effects.
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