Geometry Optimizations in a Subsystem Density Functional Theory Formalism: A Benchmark Study

Abstract

We present a benchmark study on equilibrium structures optimized with subsystem density functional theory (sDFT) employing a new analytical gradient implementation in the program SERENITY. Geometry optimizations are performed on all complexes of the S22 [Jurečka et al. Phys. Chem. Chem. Phys. 2006, 8, 1985–1993] and A24 [Řezáč and Hobza. J. Chem. Theory Comput. 2013, 9, 2151–2155] test sets. While some combinations of approximate exchange-correlation (XC) and nonadditive kinetic-energy functionals (e.g., LDA/Thomas–Fermi or PW91/PW91k) more or less successfully mimic the effect of medium-range dispersion in these complexes, we also include the combination of BP86/LLP91. This functional reproduces the dispersion problem of the corresponding BP86 Kohn–Sham (KS-)­DFT calculations and can hence successfully be corrected by empirical dispersion corrections developed for KS-DFT. We propose this as a robust and accurate strategy for sDFT geometry optimizations, which appears to be preferable over the previously used strategy relying on error cancellation between XC and nonadditive kinetic-energy functionals. In fact, the best results in our benchmark are obtained from BP86/LLP91 together with a D3-type dispersion correction. We also discuss the difference between our Gaussian-type orbital implementation in SERENITY and a Slater-type orbital based implementation in the Amsterdam density functional (ADF) program but only find small differences in most cases.

Interaction Nature and Computational Methods for Halogen Bonding: A Perspective

“…Typically, classic density functional methods, such as the BP86 and B3LYP, were not considered as suitable methods to calculate weak interactions like halogen bonds owing to the serious underestimation of dispersion effects. ,, Empirical dispersion correction schemes were developed by Grimme and coworkers to solve this problem, among which the DFT-D3 and DFT-D4 models have shown satisfactory performance in describing a variety of weak interactions. Empirical dispersion-corrected functionals such as B97-D, BP86-D, and ωB97XD have already been successfully applied in the calculation of various XB complexes. ,,,− On the other hand, Truhlar’s team developed a series of new functionals by fitting the parameters from data sets with noncovalent interactions included. − Among them, functionals represented by M06-2 X showed excellent performance in various benchmark tests ,,, and could be used as the recommended methods in describing the halogen-bonding properties. Additionally, DiLabio et al suggested that the common empirical dispersion-corrected functional methods may still have room for improvement in describing halogen bonds, especially in cases that charge transfer interactions play the significant role .…”

Theoretical investigations on P-stabilized boryl cation radicals: from the Aufbau principle to SOMO–HOMO conversion

“…It can be observed that the electronic configuration characteristics calculated at three functionals of the studied compounds are qualitatively consistent. To further confirm the effects of dispersion and the pure functional on the structural features, we also performed the calculations at the UB3LYP/6-31G(d) level, in conjunction with the D3 version of Grimme's dispersion, 27 as well as conducted optimizations on the studied compounds by using the BP86 functional, 28 and the calculated results are shown in Fig. S1 and S2 in the ESI,† respectively, both of which show a similar tendency with those results calculated at other three functionals.…”

Environmental Effects with Frozen-Density Embedding in Real-Time Time-Dependent Density Functional Theory Using Localized Basis Functions

“…Before concluding this work, it may be interesting to put forward some assessments in terms of time statistics to be used as a basis for optimizing the computation time and speed-up any uFDE-rt-TDDFT calculations. We used a water–ammonia complex as a general test-case, where the geometry of the adduct was taken from ref and water is the active subsystem.…”