Many-Body Dispersion Interactions in Molecular Crystal Polymorphism

The behavior of ice under extreme conditions undergoes the change of intermolecular binding patterns and leads to the structural phase transitions, which are needed for modeling the convection and internal structure of the giant planets and moons of the solar system as well as H2O-rich exoplanets. Such extreme conditions limit the structural explorations in laboratory but open a door for the theoretical study. The ice phases IX and XIII are located in the high pressure and low temperature region of the phase diagram. However, to the best of our knowledge, the phase transition boundary between these two phases is still not clear. In this work, based on the second-order Møller–Plesset perturbation (MP2) theory, we theoretically investigate the ice phases IX and XIII and predict their structures, vibrational spectra and Gibbs free energies at various extreme conditions, and for the first time confirm that the phase transition from ice IX to XIII can occur around 0.30 GPa and 154 K. The proposed work, taking into account the many-body electrostatic effect and the dispersion interactions from the first principles, opens up the possibility of completing the ice phase diagram and provides an efficient method to explore new phases of molecular crystals.

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First-principles stability ranking of molecular crystal polymorphs with the DFT+MBD approach

Faraday Discussions ◽

10.1039/c8fd00066b ◽

2018 ◽

Vol 211 ◽

pp. 253-274 ◽

Cited By ~ 15

Author(s):

Johannes Hoja ◽

Alexandre Tkatchenko

Keyword(s):

First Principles ◽

Structure Prediction ◽

Molecular Crystal ◽

Crystal Structure Prediction ◽

Free Energies ◽

Many Body ◽

Dispersion Effects ◽

Stability Ranking ◽

Exact Exchange ◽

The Impact

We discuss the impact of many-body dispersion effects, exact exchange, and vibrational free energies on a crystal structure prediction procedure applicable to pharmaceutically relevant systems. Furthermore, we show that this procedure is generally robust and the used approximations lead on average to changes of relative stabilities of only 1–2 kJ mol−1.

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Organic crystal polymorphism: a benchmark for dispersion-corrected mean-field electronic structure methods

Acta Crystallographica Section B Structural Science Crystal Engineering and Materials ◽

10.1107/s2052520616007885 ◽

2016 ◽

Vol 72 (4) ◽

pp. 502-513 ◽

Cited By ~ 35

Author(s):

Jan Gerit Brandenburg ◽

Stefan Grimme

Keyword(s):

Quantum Chemical ◽

Structure Prediction ◽

Density Functional ◽

Vibrational Energy ◽

Dispersion Interactions ◽

Many Body ◽

Minimal Basis ◽

Blind Test ◽

Semi Empirical ◽

The Impact

We analyze the energy landscape of the sixth crystal structure prediction blind test targets with variousfirst principlesandsemi-empiricalquantum chemical methodologies. A new benchmark set of 59 crystal structures (termed POLY59) for testing quantum chemical methods based on the blind test target crystals is presented. We focus on different means to include London dispersion interactions within the density functional theory (DFT) framework. We show the impact of pairwise dispersion corrections like the semi-empirical D2 scheme, the Tkatchenko–Scheffler (TS) method, and the density-dependent dispersion correction dDsC. Recent methodological progress includes higher-order contributions in both the many-body and multipole expansions. We use the D3 correction with Axilrod–Teller–Muto type three-body contribution, the TS based many-body dispersion (MBD), and the nonlocal van der Waals density functional (vdW-DF2). The density functionals with D3 and MBD correction provide an energy ranking of the blind test polymorphs in excellent agreement with the experimentally found structures. As a computationally less demanding method, we test our recently presented minimal basis Hartree–Fock method (HF-3c) and a density functional tight-binding Hamiltonian (DFTB). Considering the speed-up of three to four orders of magnitudes, the energy ranking provided by the low-cost methods is very reasonable. We compare the computed geometries with the corresponding X-ray data where TPSS-D3 performs best. The importance of zero-point vibrational energy and thermal effects on crystal densities is highlighted.

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