Two-component relativistic pseudopotentials (i.e., scalar-relativistic and spin–orbit (SO) potentials) of the energy-consistent variety have been adjusted for the group 11 and 12 atoms Cu, Zn; Ag, Cd; Au, Hg, replacing the 1s–2p; 1s–3d; and 1s–4f cores, respectively. The adjustment has been done for the valence-energy spectrum of (near-)neutral atoms, to reference data from numerical all-electron four-component multi-configuration Dirac–Hartree–Fock (MCDHF) calculations, including the two-electron Breit interaction. For use in molecular calculations, the potentials have been supplemented by energy-optimized (12s12p9d3f2g)/[6s6p4d3f2g] valence basis sets. First benchmark applications of the potentials and basis sets are presented for atomic excitation energies and SO splittings at a correlated level, and for ground and excited state spectroscopic properties of group 11 monohalides and group 12 dimers.

Energy-consistent pseudopotentials for group 11 and 12 atoms: adjustment to multi-configuration Dirac–Hartree–Fock data

3.1. Sc Group 6772 3.2. Ti Group 6773 3.3. V Group 6775 3.4. Cr Group 6776 3.5. Mn Group 6777 3.6. Fe Group 6779 3.7. Co Group 6780 3.8. Ni Group 6782 3.9. Cu Group 6782 3.10. Zn Group 6784 3.11. Lanthanide Group 6784 3.12. Actinide Group 6785 3.13. Periodic Trends on Bonding and Reactivity 6785 4. Ionic Mononuclear Transition Metal Oxide Species 6787 4.1. Cations 6788 4.2. Anions 6790 4.2.1. Monoxide Anions 6790 4.2.2. Dioxide Anions 6791 4.2.3. Oxygen-Rich Anions 6792 5. Multinuclear Transition Metal Oxide Clusters 6792 5.1. Sc Group 6793 5.2. Ti Group 6793 5.3. V Group 6793 5.4. Cr Group 6797 5.5. Mn Group 6798 5.6. Fe Group 6798 5.7. Co Group 6798 5.8. Ni Group 6798 5.9. Cu Group 6799 6. Summary 6800 7. Acknowledgments 6800 8. References 6800

Spectroscopic and theoretical studies of transition metal oxides and dioxygen complexes.

Understanding the nature of the transition-metal (TM)-main-group-element bond is important in many areas of science, such as organometallic chemistry,1,2 surface science,3 catalysis,4 high-temperature chemistry,5,6 and astrophysics.7,8 For example, the oxides are of interest to astrophysics as the constituents of cool stars and to surface science as zero-order models for the oxidation of a transition-metal surface.9 These systems are electronically complex and very difficult to treat theoretically. Indeed, while the use of quantum chemistry to obtain useful and reliable information about small organic molecules is now routine,11 a very different situation arises in the theoretical description of molecules containing a transition element. This is due to several factors, but the most important is that the extent of electron correlation required for even qualitatively correct results is significantly raised relative to molecules containing only main-group elements. The correlation between the electronic states of a molecule and the states of its constituent atoms has been an important concept in chemistry and physics for many years. For example, we know that if a molecule is composed of atoms that have large energy differences between their various electronic states, the molecule will be characterized by electronic states that are widely spaced, or granular. In the context of the preeminent orbital theory, the Hartree-Fock (HF) theory, this means that the molecular orbitals of molecules formed from these atoms will be widely spaced in energy, and the HF configuration will dominate the wave function around equilibrium. This is, of course, the reason the HF theory has achieved its unique role as both an interpretive and predictive tool in the chemistry of the firstand second-row, main-group elements. While the situation becomes somewhat flawed as one moves away from equilibrium structures, the conceptual simplicity and interpretability of the orbital picture can be preserved by constructing self-consistent wave functions in which the HF configuration is augmented by one or more configurations. This multiconfiguration, self-consistent field (MCSCF) approach is capable, in principle, of providing a uniform description of the evolution 679 Chem. Rev. 2000, 100, 679−716

Electronic structure of diatomic molecules composed of a first-row transition metal and main-group element (h-f).

With the objective of analyzing which kind of reference data is appropriate for benchmarking quantum chemical approaches for transition metal compounds, we present the following, (a) a collection of 60 transition metal diatomic molecules for which experimentally derived dissociation energies, equilibrium distances, and harmonic vibrational frequencies are known and (b) a composite computational approach based on coupled-cluster theory with basis set extrapolation, inclusion of core–valence correlation, and corrections for relativistic and multireference effects The latter correction was obtained from internally contracted multireference coupled-cluster (icMRCC) theory This composite approach has been used to obtain the dissociation energies and spectroscopic constants for the 60 molecules in our data set In accordance with previous studies on a subset of molecules, we find that multireference corrections are rather small in many cases and CCSD(T) can provide accurate reference values, if the complete b

How To Arrive at Accurate Benchmark Values for Transition Metal Compounds: Computation or Experiment?

Core-valence basis sets for the alkali and alkaline earth metals Li, Be, Na, Mg, K, and Ca are proposed. The basis sets are validated by calculating spectroscopic constants of a variety of diatomic molecules involving these elements. Neglect of (3s, 3p) correlation in K and Ca compounds will lead to erratic results at best, and chemically nonsensical ones if chalcogens or halogens are present. The addition of low-exponent p functions to the K and Ca basis sets is essential for the smooth convergence of molecular properties. Inclusion of inner-shell correlation is important for accurate spectroscopic constants and binding energies of all the compounds. In basis set extrapolation/convergence calculations, the explicit inclusion of alkali and alkaline earth metal subvalence correlation at all steps is essential for K and Ca, strongly recommended for Na, and optional for Li and Mg, while in Be compounds an additive treatment in a separate ‘core correlation’ step is probably sufficient. Consideration of (ls) i...

Alkali and alkaline earth metal compounds: core-valence basis sets and importance of subvalence correlation

Laser-Induced Fluorescence and Fourier Transform Spectroscopy of the [21.9]2Δ5/2–X2Π3/2 (21 910 cm−1) and the [21.9]2Δ5/2–[.16]2Δ5/2 (21 750 cm−1) Transitions of NiCl

B. Pinchemel

Papers

Laser-Induced Fluorescence and Fourier Transform Spectroscopy of the [21.9]2Δ5/2–X2Π3/2 (21 910 cm−1) and the [21.9]2Δ5/2–[.16]2Δ5/2 (21 750 cm−1) Transitions of NiCl

Laser-Induced Fluorescence and Fourier Transform Spectroscopy of NiCl: Identification of a Low-Lying 2Σ+ State (1768 cm−1)

The Blue-Violet Transitions of NiF: Identification of a New Low-Lying 2Σ State (T0 = 252 cm−1)

Fourier Transform Spectroscopy of the A′1Π–X1Σ+ System of CaO

The electronic valence states of CuO: An energy level diagram