Ab initio effective core potentials (ECP’s) have been generated to replace the Coulomb, exchange, and core‐orthogonality effects of the chemically inert core electron in the transition metal atoms Sc to Hg. For the second and third transition series relative ECP’s have been generated which also incorporate the mass–velocity and Darwin relativistic effects into the potential. The ab initio ECP’s should facilitate valence electron calculations on molecules containing transition‐metal atoms with accuracies approaching all‐electron calculations at a fraction of the computational cost. Analytic fits to the potentials are presented for use in multicenter integral evaluation. Gaussian orbital valence basis sets are developed for the (3d,4s,4p), (4d,5s,5p), and (5d,6s,6p) orbitals of the first, second, and third transition series atoms, respectively. All‐electron and valence‐electron atomic excitation energies are also compared for the low‐lying states of Sc–Hg, and the valence‐electron calculations are found to reproduce the all‐electron excitation energies (typically within a few tenths of an eV).

Ab initio effective core potentials for molecular calculations. Potentials for the transition metal atoms Sc to Hg

Nitrogen (N)-doped carbon materials exhibit high electrocatalytic activity for the oxygen reduction reaction (ORR), which is essential for several renewable energy systems. However, the ORR active site (or sites) is unclear, which retards further developments of high-performance catalysts. Here, we characterized the ORR active site by using newly designed graphite (highly oriented pyrolitic graphite) model catalysts with well-defined π conjugation and well-controlled doping of N species. The ORR active site is created by pyridinic N. Carbon dioxide adsorption experiments indicated that pyridinic N also creates Lewis basic sites. The specific activities per pyridinic N in the HOPG model catalysts are comparable with those of N-doped graphene powder catalysts. Thus, the ORR active sites in N-doped carbon materials are carbon atoms with Lewis basicity next to pyridinic N.

Active sites of nitrogen-doped carbon materials for oxygen reduction reaction clarified using model catalysts

Today, coupled-cluster theory offers the most accurate results among the practical ab initio electronic-structure theories applicable to moderate-sized molecules. Though it was originally proposed for problems in physics, it has seen its greatest development in chemistry, enabling an extensive range of applications to molecular structure, excited states, properties, and all kinds of spectroscopy. In this review, the essential aspects of the theory are explained and illustrated with informative numerical results.

/pdf/coupled-cluster-theory-in-quantum-chemistry-nnwxwp80ej.pdf

Coupled-cluster theory in quantum chemistry

Physical Review B

https://courses.washington.edu/cfr523/documents/Alonso2010CatalyticConversion.pdf

Catalytic conversion of biomass to biofuels

The 5s-5p electric-dipole resonance transitions in highly ionized promethiumlike ions have been studied applying relativistic multi-reference Moeller-Plesset second-order perturbation theory. The transition wavelengths are determined to within 0.2 {angstrom} in the more highly charged ions, where the level degeneracies are small. For somewhat lighter ions a very large reference space was used in order to account for the many degeneracies. In order to calculate transition probabilities and lifetimes, correlation corrections have been added to the transition operator in the next order. The contributions from the higher orders of the theory, that is, frequency-dependent Breit correction, Lamb shift, and mass shifts, have been estimated. The results are used to re-assess spectroscopic data from beam-foil, electron beam ion trap, and tokamak observations.

/pdf/electric-dipole-5s-5p-transitions-in-promethiumlike-ions-s9enu7hhwi.pdf

Electric-dipole 5s - 5p Transitions in Promethiumlike Ions

Density functional calculations on CO attached to PtnRu(10−n) (n = 6–10) clusters

The electronic properties of DNA-DNA and PNA-DNA double strands having 3-6 base pairs (bp) were investigated by density functional theory (DFT) calculations. The binding energies and the highest occupied molecular orbital-lowest unoccupied molecular orbital (HOMO-LUMO) energy gaps for the PNA-DNA hybrids in the vapor phase are found to be greater than those for the DNA-DNA hybrids, regardless of the number of base pairs involved. The study supports the experimental finding that PNA displays high affinity toward a complementary DNA and that PNA-DNA strands are much more thermodynamically stable than their DNA-DNA counterparts. The results suggest much higher sensitivity in DNA sequencing with the arrays of PNA than with those of DNA.

Yasuyuki Ishikawa

Papers

Electric-dipole 5s - 5p Transitions in Promethiumlike Ions

Density functional calculations on CO attached to PtnRu(10−n) (n = 6–10) clusters

DFT study of the electronic properties of DNA–DNA and PNA–DNA double strands

Fully numerical solutions of the molecular Schrödinger equation in momentum space

Ab initio Dirac—Fock self-consistent field calculations for open-shell heavy-atom systems: bonding in AuH+ ion