Closed-shell interaction in silver and gold chlorides

Hartree-Fock and coupled-cluster calculations have been performed for cubic AgCl and for AuCl having a cubic or the observed structure with space group I4_1/amd. Cohesive energies and lattice constants are in excellent agreement with experiment for AgCl; for AuCl we find good agreement, and the experimental structure is correctly predicted to be lower in energy than the cubic one. Electron-correlation effects on lattice constants are very large, of up to 0.8 \AA for cubic AuCl. We especially discuss the strength of the closed-shell interactions, and for the first time a quantitative analysis of the so-called "aurophilic" Au(I)-Au(I) interaction is presented in solids.Comment: accepted by J. Chem. Phy

Recurrence and differential relations for spherical spinors

We present a comprehensive table of recurrence and differential relations obeyed by spin one-half spherical spinors (spinor spherical harmonics) $\Omega_{\kappa\mu}(\mathbf{n})$ used in relativistic atomic, molecular, and solid state physics, as well as in relativistic quantum chemistry. First, we list finite expansions in the spherical spinor basis of the expressions $\mathbf{A}\cdot\mathbf{B}\,\Omega_{\kappa\mu}(\mathbf{n})$ and {$\mathbf{A}\cdot(\mathbf{B}\times\mathbf{C})\, \Omega_{\kappa\mu}(\mathbf{n})$}, where $\mathbf{A}$, $\mathbf{B}$, and $\mathbf{C}$ are either of the following vectors or vector operators: $\mathbf{n}=\mathbf{r}/r$ (the radial unit vector), $\mathbf{e}_{0}$, $\mathbf{e}_{\pm1}$ (the spherical, or cyclic, versors), $\boldsymbol{\sigma}$ (the $2\times2$ Pauli matrix vector), $\hat{\mathbf{L}}=-i\mathbf{r}\times\boldsymbol{\nabla}I$ (the dimensionless orbital angular momentum operator; $I$ is the $2\times2$ unit matrix), $\hat{\mathbf{J}}=\hat{\mathbf{L}}+1/2\boldsymbol{\sigma}$ (the dimensionless total angular momentum operator). Then, we list finite expansions in the spherical spinor basis of the expressions $\mathbf{A}\cdot\mathbf{B}\,F(r)\Omega_{\kappa\mu}(\mathbf{n})$ and $\mathbf{A}\cdot(\mathbf{B}\times\mathbf{C})\, F(r)\Omega_{\kappa\mu}(\mathbf{n})$, where at least one of the objects $\mathbf{A}$, $\mathbf{B}$, $\mathbf{C}$ is the nabla operator $\boldsymbol{\nabla}$, while the remaining ones are chosen from the set $\mathbf{n}$, $\mathbf{e}_{0}$, $\mathbf{e}_{\pm1}$, $\boldsymbol{\sigma}$, $\hat{\mathbf{L}}$, $\hat{\mathbf{J}}$.Comment: LaTeX, 12 page

Homogeneous Gold Catalysis through Relativistic Effects: Addition of Water to Propyne

In the catalytic addition of water to propyne the Au(III) catalyst is not stable under non-relativistic conditions and dissociates into a Au(I) compound and Cl2. This implies that one link in the chain of events in the catalytic cycle is broken and relativity may well be seen as the reason why Au(III) compounds are effective catalysts.Comment: 12 pages, 3 figures, 1 tabl

Symmetry and Electronic Structure of Noble Metal Nanoparticles and the Role of Relativity

High resolution photoelectron spectra of cold mass selected Cu_n-, Ag_n- and Au_n- with n =53-58 have been measured at a photon energy of 6.42 eV. The observed electron density of states is not the expected simple electron shell structure, but seems to be strongly influenced by electron-lattice interactions. Only Cu55- and Ag55- exhibit highly degenerate states. This is a direct consequence of their icosahedral symmetry, as is confirmed by density functional theory calculations. Neighboring sizes exhibit perturbed electronic structures, as they are formed by removal or addition of atoms to the icosahedron and therefore have lower symmetries. Gold clusters in the same size range show completely different spectra with almost no degeneracy, which indicates that they have structures of much lower symmetry. This behaviour is related to strong relativistic bonding effects in gold, as demonstrated by ab initio calculations for Au55-.Comment: 10 pages, 3 figure

Higher order Schrodinger and Hartree-Fock equations

The domain of validity of the higher-order Schrodinger equations is analyzed for harmonic-oscillator and Coulomb potentials as typical examples. Then the Cauchy theory for higher-order Hartree-Fock equations with bounded and Coulomb potentials is developed. Finally, the existence of associated ground states for the odd-order equations is proved. This renders these quantum equations relevant for physics.Comment: 19 pages, to appear in J. Math. Phy

Embedding Transition-Metal Atoms in Graphene: Structure, Bonding, and Magnetism

We present a density-functional-theory study of transition-metal atoms (Sc–Zn, Pt, and Au) embedded in single and double vacancies (SV and DV) in a graphene sheet. We show that for most metals, the bonding is strong and the metal-vacancy complexes exhibit interesting magnetic behavior. In particular, an Fe atom on a SV is not magnetic, while the Fe@DV complex has a high magnetic moment. Surprisingly, Au and Cu atoms at SV are magnetic. Both bond strengths and magnetic moments can be understood within a simple local-orbital picture, involving carbon sp2 hybrids and the metal spd orbitals. We further calculate the barriers for impurity-atom migration, and they agree well with available experimental data. We discuss the experimental realization of such systems in the context of spintronics and nanocatalysis.Peer reviewe

Cohesive properties of alkali halides

We calculate cohesive properties of LiF, NaF, KF, LiCl, NaCl, and KCl with ab-initio quantum chemical methods. The coupled-cluster approach is used to correct the Hartree-Fock crystal results for correlations and to systematically improve cohesive energies, lattice constants and bulk moduli. After inclusion of correlations, we recover 95-98 % of the total cohesive energies. The lattice constants deviate from experiment by at most 1.1 %, bulk moduli by at most 8 %. We also find good agreement for spectroscopic properties of the corresponding diatomic molecules.Comment: LaTeX, 10 pages, 1 figure, accepted by Phys. Rev.

g factor of Li-like ions with nonzero nuclear spin

The fully relativistic theory of the g factor of Li-like ions with nonzero nuclear spin is considered for the (1s)^2 2s state. The magnetic-dipole hyperfine-interaction correction to the atomic g factor is calculated including the one-electron contributions as well as the interelectronic-interaction effects of order 1/Z. This correction is combined with the interelectronic-interaction, QED, nuclear recoil, and nuclear size corrections to obtain high-precision theoretical values for the g factor of Li-like ions with nonzero nuclear spin. The results can be used for a precise determination of nuclear magnetic moments from g factor experiments.Comment: 20 pages, 5 figure

Elastic and vibrational properties of alpha and beta-PbO

The structure, electronic and dynamic properties of the two layered alpha (litharge) and beta (massicot) phases of PbO have been studied by density functional methods. The role of London dispersion interactions as leading component of the total interaction energy between layers has been addressed by using the Grimme's approach, in which new parameters for Pb and O atoms have been developed. Both gradient corrected and hybrid functionals have been adopted using Gaussian-type basis sets of polarized triple zeta quality for O atoms and small core pseudo-potential for the Pb atoms. Basis set superposition error (BSSE) has been accounted for by the Boys-Bernardi correction to compute the interlayer separation. Cross check with calculations adopting plane waves that are BSSE free have also been performed for both structures and vibrational frequencies. With the new set of proposed Grimme's type parameters structures and dynamical parameters for both PbO phases are in good agreement with experimental data.Comment: 8 pages, 5 figure