In the past decade, a number of approaches have been developed to fix the failure of (semi)local density-functional theory (DFT) in describing intermolecular interactions. The performance of several such approaches with respect to highly accurate benchmarks is compared here on a set of separation-dependent interaction energies for ten dimers. Since the benchmarks were unknown before the DFT-based results were collected, this comparison constitutes a blind test of these methods.

In this article, we show that the long-range-corrected (LC) density functionals LC-BOP and LCgau-BOP reproduce frontier orbital energies and highest-occupied molecular orbital (HOMO)-lowest-unoccupied molecular orbital (LUMO) gaps better than other density functionals. The negative of HOMO and LUMO energies are compared with the vertical ionization potentials (IPs) and electron affinities, respectively, using CCSD(T)/6-311++G(3df,3pd) for 113 molecules, and we found LC functionals to satisfy Koopmans' theorem. We also report that the frontier orbital energies and the HOMO-LUMO gaps of LC-BOP and LCgau-BOP are better than those of recently proposed ωM05-D (Lin et al., J. Chem. Phys. 2012, 136, 154109). We express the exact IP in terms of orbital relaxation, and correlation energies and hence calculate the relaxation and correlation energies for the same set of molecules. It is found that the LC functionals, in general, includes more relaxation effect than Hartree-Fock and more correlation effect than the other density functionals without LC scheme. Finally, we scan μ parameter in LC scheme from 0.1 to 0.6 bohr(-1) for the above test set molecules with LC-BOP functional and found our parameter value, 0.47 bohr(-1), is usefully applicable to our tested systems.

System-dependent nonempirical tuning of range-separated functional provides a way to minimize the delocalization error of the system. However, existing nonempirical tuning method requires the computation of several ΔSCF calculations to determine the optimal μ value. In this article, we have defined a scheme to evaluate the optimal μ value with single self-consistent field calculation. Our method is based on the evaluation of the spherically symmetric average Electron localization function (ELF) region. According to this scheme, the radius of the spherically symmetric average ELF region gives is a measure of the distance at which the long-range part of the range-separated functional becomes dominant. Numerical results indicate that our method improves the reproduction of HOMO energies and HOMO-LUMO gap in comparison to global and IP-tuned range-separated functional. Moreover, in case of HOMO energies, maximum error of the ELF-tuned functional is considerably smaller than the global and IP-tuned functional. Furthermore, our method gives considerably smaller deviation of HOMO energies from ΔSCF IP than global range-separated functional. © 2017 Wiley Periodicals, Inc.

We analyze the antioxidant property of four phenolic compounds i.e., gallic acid, methyl gallate, ethyl gallate, and 4, 5-dihydroxy 3-methoxy benzoic acid through the determination of bond dissociation enthalpy (BDE), vertical ionization potential ( IP v) in gas phase as well as in six different solvent medium. The theoretical trends of these phenolic compounds, based on BDE and IP, is compared with the scavenging activity towards HOCl . In addition, we compute and analyze the values of the density-based reactivity descriptors such as chemical potential, hardness, electrophilicity, and local softness.