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

Recently we developed generator coordinate Dirac–Fock and Dirac–Fock–Breit methods for closed-shell systems assuming finite nucleus and have reported Dirac–Fock and Dirac–Fock–Breit energies for the atoms He through Nobelium (Z=102) [see Refs. Reference 10Reference 11Reference 12Reference 13]. In this paper, we generalize our earlier work on closed-shell systems and develop a generator coordinate Dirac–Fock method for open-shell systems. We present results for a number of representative open-shell heavy atoms (with nuclear charge Z>80) including the actinide and superheavy transactinide (with Z>103) atomic systems: Fr (Z=87), Ac (Z=89), and Lr (Z=103) to E113 (eka-thallium, Z=113). The high accuracy obtained in our open-shell Dirac–Fock calculations is similar to that of our closed-shell calculations, and we attribute it to the fact that the representation of the relativistic dynamics of an electron in a spherical ball finite nucleus near the origin in terms of our universal Gaussian basis set is as accur...

The generator coordinate Dirac-Fock method for open-shell atomic systems

A density-functional study of the energetics of H2O dissociation on bimetallic Pt/Ru nanoclusters

The use of Gaussian spinors in relativistic electronic structure calculations: the effect of the boundary of the finite nucleus of uniform proton charge distribution

The frequency-independent Breit interaction, which gives the leading correction to the instantaneous Coulomb interaction, is treated self-consistently in matrix Dirac–Fock–Breit self-consistent field (SCF) calculations. Calculations were done on He, He-like ions, Be, Be-like ions, Ne, and Ar. Basis sets of even- and well-tempered Gaussian functions were used to expand the large and small components of Dirac 4-spinors. The results of the variational calculations are compared with Desclaux's benchmark numerical perturbative calculations.

Yasuyuki Ishikawa

Papers

The generator coordinate Dirac-Fock method for open-shell atomic systems

A density-functional study of the energetics of H2O dissociation on bimetallic Pt/Ru nanoclusters

The use of Gaussian spinors in relativistic electronic structure calculations: the effect of the boundary of the finite nucleus of uniform proton charge distribution

Atomic Dirac–Fock–Breit self-consistent field calculations

Direct ab initio molecular dynamics study of C++H2O