Tuning the quasi‐harmonic treatment of crystalline ionic liquids within the density functional theory

Abstract

Five ionic liquids are selected for benchmarking the performance of quasi‐harmonic density functional theory (DFT) calculations of structural, phonon, and thermodynamic properties of their crystals. Data predicted by individual computational setups are sorted, establishing a distinct hierarchy among the first‐principles approaches. PBE‐D3 and B3LYP‐D3 functionals are coupled with various plane wave and Gaussian‐type orbital (GTO) basis sets. Propagation of the basis set superposition error and of the imperfections of both functionals into finite‐temperature properties is discussed in detail. PBE‐D3 together with a triple‐zeta GTO basis set often yields the most accurate predictions of predicted molar volume and heat capacity with errors at 1% and 8%, respectively, representing the state‐of‐the‐art for quasi‐harmonic DFT calculations for crystalline ionic liquids. Fortuitous error cancellation between the basis‐set superposition (overbinding) and PBE imperfection (overexpanding) strongly affects the overall accuracy, unlike the case of B3LYP/GTO calculations, impeding systematic convergence of the methodology towards higher accuracy.

Dynamic disorder, Strain and Sublimation of Crystalline Caged Hydrocarbons from First Principles

“…Our calculations range close to the other reference value of 55.2 ± 2.0 kJ mol −1 , reported by Bashir-Hashemi et al 27 Still, there is some residual computational uncertainty of our computational model, amounting to 2-3%, 97 representing here 1-2 kJ mol −1 . This uncertainty is mostly related to the model of many-body dispersion interactions in crystalline cubane.…”

“…Based on the above mentioned hypothesis, and on our experience with the performance of these two functionals when coupled with the pob-TZVP-ref2 basis set in the quasi-harmonic approximation 97 and the fragment-based model 98 Our best calculation of the sublimation enthalpy yields a value 55.9 kJ mol −1 at 298 K. As such, it suggests that the original experimental value of 80.3 ± 1.7 kJ mol −1 reported by Kybett et al, 28 which also violates general correlation between sublimation enthalpy and molar mass that is valid for other hydrocarbons, as noted by Diky et al 19 , seems to be largely overestimated.…”

Regulating the Electronic Configuration of Spinel Zinc Manganate Derived from Metal–Organic Frameworks: Controlled Synthesis and Application in Anode Materials for Lithium-Ion Batteries

“…The DFT calculations were performed by the Vienna Ab-initio Simulation Package (VASP) , with the frozen-core all-electron projector-augment-wave (PAW) , method. The Perdew–Burke–Ernzerhof (PBE) of generalized gradient approximation (GGA) was used to discuss the exchange and correlation potential. A 2 × 1 × 1 ZnMn 2 O 4 supercell was used.…”

Anisotropy, segmental dynamics and polymorphism of crystalline biogenic carboxylic acids

“…46,95 Note that testing other popular DFT functionals and basis sets did not bring any significant systematic entropy improvement for molecular crystals. 96 Corresponding errors of properties of individual polymorphs are likely to cancel out to some extent, but still, such an uncertainty still appears to be too large for generally reliable polymorph ranking at elevated temperatures. High-temperature tails of predicted Δ G ( T ) and Δ H ( T ) curves exhibiting bizarre slopes above 400 K in Fig.…”