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The many-body expansion, where one computes the total energy of a supersystem as the sum of the dimer, trimer, tetramer, etc., subsystems, provides a convenient approach to compute the lattice energies of molecular crystals. We investigate approximate methods for computing the non-additive three-body contributions to the crystal lattice energy of the polar molecules acetic acid, imidazole, and formamide, comparing to coupled-cluster singles, doubles, and perturbative triples [CCSD(T)] level benchmarks. Second-order Møller–Plesset perturbation theory (MP2), if combined with a properly damped Axilrod–Teller–Muto dispersion potential, displays excellent agreement with CCSD(T) at a substantially reduced cost. Errors between dispersion-corrected MP2 and CCSD(T) are less than 1 kJ mol−1 for all three crystals. However, the three-body energy requires quite large distance cutoffs to converge, up to 20 Å or more.
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Range-dependence of two-body intermolecular interactions and their energy components in molecular crystals
Routinely assessing the stability of molecular crystals with high accuracy remains an open challenge in the computational sciences. The many-body expansion decomposes computation of the crystal lattice energy into an embarrassingly parallel collection of computations over molecular dimers, trimers, and so forth, making quantum chemistry techniques tractable for many crystals of small organic molecules. By examining the range-dependence of different types of energetic contributions to the crystal lattice energy, we can glean qualitative understanding of solid-state intermolecular interactions as well as practical, exploitable reductions in the number of computations required for accurate energies. Here, we assess the range-dependent character of two-body interactions of 24 small organic molecular crystals by using the physically interpretable components from symmetry-adapted perturbation theory (electrostatics, exchange-repulsion, induction/polarization, and London dispersion). We also examine correlations between the convergence rates of electrostatics and London dispersion terms with molecular dipole moments and polarizabilities, to provide guidance for estimating convergence rates in other molecular crystals.
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- PAR ID:
- 10353742
- Date Published:
- Journal Name:
- The Journal of Chemical Physics
- Volume:
- 157
- Issue:
- 8
- ISSN:
- 0021-9606
- Page Range / eLocation ID:
- 084503
- Format(s):
- Medium: X
- Sponsoring Org:
- National Science Foundation
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Accepted Manuscript1.0
- Journal Article:
- https://doi.org/10.1063/5.0103644
