Accurate universal Gaussian basis set for hydrogen through lanthanum generated with the generator coordinate Hartree-Fock method

The Dual Descriptor Reveals the Janus–Faced Behaviour of Diiodine

The Janus–faced ligand behavior of diiodine (I₂) was evidenced after applying the dual descriptor (DD or second-order Fukui function), thus providing additional support to the work performed by Rogachev and Hoffmann in 2013. Along with its capacity to reveal sites susceptible to undergo attacks simultaneously of nucleophilic and electrophilic types, another advantage of DD lies in being an orbital-free descriptor. That means it is based only upon total electron densities when written in its most accurate operational formula. This quality is not exclusive of DD because when Fukui functions are written in terms of electron densities instead of densities of frontier molecular orbitals, they become orbital-free descriptors too. Furthermore, the present work is an application of the generalized operational formula of the dual descriptor published in 2016 that takes into account any possible degeneracy in frontier molecular orbitals. As a proof about capabilities of DD, the possible sites for a favorable interaction between I₂ with two organometallic compounds [Rh₂(O₂CCF₃)₄] and [(C₈H₁₁N₂)Pt (CH₃)] were correctly revealed by overlapping the biggest lobe for receiving nucleophilic attacks of one molecule with the biggest lobe for receiving electrophilic attacks of the other molecule, so allowing to predict the same coordination modes as experimentally known: linear “end–on” for the [(C₈H₁₁N₂)Pt (CH₃)]…I₂, and bent “end–on” for the [Rh₂(O₂CCF₃)₄]…I₂ interactions.

Atomic photoionization cross sections beyond the electric dipole approximation

A methodology is developed to compute photoionization cross sections beyond the electric dipole approximation from response theory, using Gaussian type orbitals and plane waves for the initial and final states, respectively. The methodology is applied to compute photoionization cross sections of atoms and ions from the first four rows of the periodic table. Analyzing the error due to the plane wave description of the photoelectron, we find kinetic energy and concomitant photon energy thresholds above which the plane wave approximation becomes applicable. The correction introduced by going beyond the electric dipole approximation increases with photon energy and depends on the spatial extension of the initial state. In general, the corrections are below 10% for most elements, at a photon energy reaching up to 12 keV.

Reducing density-driven error without exact exchange

PBE calculations, performed non-self-consistently on densities evaluated with Rung 3.5 density functionals, give improved performance for hydrogen transfer reaction barriers.

Parameterized local hybrid functionals from density-matrix similarity metrics

We recently proposed a real-space similarity metric comparing the Kohn-Sham one-particle density matrix to the local spin-density approximation model density matrix [Janesko and Scuseria, J. Chem. Phys. 127, 164117 (2007)]. This metric provides a useful ingredient for constructing local hybrid density functionals that locally mix exact exchange and semilocal density functional theory exchange. Here we present two lines of inquiry: An approximate similarity metric comparing exact versus generalized gradient approximation (GGA), exchange and parameterized mixing functions using these similarity metrics. This approach yields significantly improved thermochemistry, including GGA local hybrids whose thermochemical performance approaches GGA global hybrids.

Local hybrid functionals based on density matrix products

We present a novel similarity metric comparing exact and semilocal density functional theory (DFT) exchange holes in real space. This metric is obtained from the product of the one-particle density matrix and the uniform electron gas model density matrix. The metric is bound between 0 and 1, 1 in the uniform electron gas, 0 in regions asymptotically far from finite systems, and can detect delocalization of the exact exchange hole and effective fractional occupations. We also present a parameter-free local hybrid functional that uses this similarity metric to locally mix exact and semilocal DFT exchange energy densities. The resulting functional gives better thermochemistry and reaction barrier heights than our original local hybrids [Jaramillo et al., J. Chem. Phys. 118, 1068 (2003)], while retaining moderate accuracy for symmetric radical cation dimers.

Optical constants, dielectric constants, molar absorption coefficients, molar polarizability, vibrational assignment and transition moments of liquid iodobenzene between 4000 and 400 cm(-1) at 25 degrees C

This paper reports the complex refractive index, molar absorption coefficient and imaginary molar polarizability spectra of liquid iodobenzene at 25 degrees C. The imaginary molar polarizability spectrum was fitted with 184 classical damped harmonic bands to determine the integrated intensity of the individual transitions. The standard deviation of the fitted spectrum from the experimental spectrum is 0.024 cm(3) mol(-1), and the R(2) value of the fit is 0.9968 indicating that the fitted spectrum is an accurate representation of the experimental spectrum. The dipole moment derivatives with respect to the normal coordinates and transition moments were determined for 26 of the 30 fundamentals. The total intensities of the in-plane and out-of-plane fundamentals were compared to benzene and other monosubstituted benzene derivatives using the F-sum rule. It was found that the total intensity of the out-of-plane fundamentals is essentially the same for the different compounds while the total intensities for the in-plane fundamentals varies according to the electronegativities of the substituents.