GGA-Level Subsystem DFT Achieves Sub-kcal/mol Accuracy Intermolecular Interactions by Mimicking Nonlocal Functionals

Benchmark tests of a strongly constrained semilocal functional with a long-range dispersion correction

The strongly constrained and appropriately normed (SCAN) semilocal density functional [J. Sun, A. Ruzsinszky, J. P. Perdew \textit{Phys. Rev. Lett.} {\bf 115}, 036402 (2015)] obeys all 17 known exact constraints for meta-generalized-gradient approximations (meta-GGA) and includes some medium range correlation effects. Long-range London dispersion interactions are still missing, but can be accounted for via an appropriate correction scheme. In this study, we combine SCAN with an efficient London dispersion correction and show that lattice energies of simple organic crystals can be improved with…

量子效应还是理论假象？氢高压相稳定性与性质的计算再分析

-Quantum Effects or Theoretical Artifacts? A Computational Reanalysis of Hydrogen's High-Pressure Phase Stability and Properties

通过meta-GGA泛函（R2SCAN和SCAN0）与GGA-PBE泛函对比，发现PBE高估分子相稳定性，而meta-GGA更接近扩散蒙特卡洛结果，表明PBE预测的动力学不稳定性和非谐性可能源于泛函缺陷而非量子核效应。

Very strong chalcogen bonding: Is oxygen in molecules capable of forming it? A First Principles Perspective

There are views prevalent in the noncovalent chemistry literature that i) the O atom in molecules cannot form a chalcogen bond, and ii) if formed, this bond is very weak. We have shown in this study that these views are not necessarily true since the attractive energy between the oxygen atom of some molecules and several electron rich anionic bases examined in a series of 34 ion-molecule complexes varied from the weak (ca -2.30 kcal/mol) to the ultrastrong (-90.10 kcal/mol). The [MP2/aug-cc-pVTZ] binding energies for several of these complexes were found to be comparable to or significantly la…

Extension of the B3LYP - Dispersion-Correcting Potential Approach to the Accurate Treatment of both Inter- and Intramolecular Interactions

We recently showed that dispersion-correcting potentials (DCPs), atom-centered Gaussian-type functions developed for use with B3LYP (J. Phys. Chem. Lett. 2012, 3, 1738-1744) greatly improved the ability of the underlying functional to predict non-covalent interactions. However, the application of B3LYP-DCP for the β-scission of the cumyloxyl radical led a calculated barrier height that was over-estimated by ca. 8 kcal/mol. We show in the present work that the source of this error arises from the previously developed carbon atom DCPs, which erroneously alters the electron density in the C-C cov…

电活性聚合物PVDF和P（VDF-TrFE）能量学和动力学的密度泛函理论和分子动力学研究

Density Functional Theory and Molecular Dynamics Studies on Energetics and Kinetics for Electro-Active Polymers: PVDF and P(VDF-TrFE)

采用第一性原理方法研究了铁电聚合物聚偏氟乙烯（PVDF）及其与三氟乙烯（TrFE）的共聚物的静态和动态力学性能。我们使用密度泛函理论[在广义梯度近似（DFT-GGA）]计算PVDF和P（VDF-TrFE）的各种晶相的结构和能量。我们发现，PVDF的最低能量相是一个非极性晶体与反式（T）和左（G）键的组合;在共聚物的情况下，额外的（庞大的）F原子的作用是稳定T键。这导致实验观察到的更高的结晶度和压电性。使用基于MSXX第一性原理的力场（FF）与分子动力学（MD），我们发现，在一个全T晶体中的成核扭结（由反式键分离的gauche对）所需的能量势垒是低得多（14.9千卡/摩尔）在P（VDF-TrFE）共聚物比在PVDF（24.8千卡/摩尔）。这与以下观察结果相关：共聚物的极性相在加热下表现出固-固向非极性相的转变，而PVDF直接熔融。我们还研究了单轴应力下极性和非极性相之间的界面的流动性，我们发现一个较低的阈值应力和较高的流动性的共聚物相比，PVDF。最后，考虑到施加剪切下的塑性形变，我们发现P（VDF-TrFE）的链具有非常低的滑动阻力，特别是沿着链方向。这些“单元机制”的原子表征为电活性聚合物的介观或宏观模型提供了必要的输入。

The Elephant in the Room of Density Functional Theory Calculations

Using multiwavelets, we have obtained total energies and corresponding atomization energies for the GGA-PBE and hybrid-PBE0 density functionals for a test set of 211 molecules with an unprecedented and guaranteed $μ$Hartree accuracy. These quasi-exact references allow us to quantify the accuracy of standard all-electron basis sets that are believed to be highly accurate for molecules, such as Gaussian-type orbitals (GTOs), all-electron numeric atom-centered orbitals (NAOs) and full-potential augmented plane wave (APW) methods. We show that NAOs are able to achieve the so-called chemical accura…