Magnetically tunable Feshbach resonances in ultracold Li-Yb mixtures.

We investigate the possibility of forming Li+Yb ultracold molecules by magnetoassociation in mixtures of ultracold atoms. We find that magnetically tunable Feshbach resonances exist, but are extremely narrow for even-mass ytterbium isotopes, which all have zero spin. For odd-mass Yb isotopes, however, there is a new mechanism due to hyperfine coupling between the electron spin and the Yb nuclear magnetic moment.

Simultaneous bridge-localized and mixed-valence character in diruthenium radical cations featuring diethynylaromatic bridging ligands.

A series of bimetallic ruthenium complexes [{Ru(dppe)Cp*}(2)(μ-C≡CArC≡C)] featuring diethynylaromatic bridging ligands (Ar = 1,4-phenylene, 1,4-naphthylene, 9,10-anthrylene) have been prepared and some representative molecular structures determined. A combination of UV-vis-NIR and IR spectroelectrochemical methods and density functional theory (DFT) have been used to demonstrate that one-electron oxidation of compounds [{Ru(dppe)Cp*}(2)(μ-C≡CArC≡C)](HC≡CArC≡CH = 1,4-diethynylbenzene; 1,4-diethynyl-2,5-dimethoxybenzene; 1,4-diethynylnaphthalene; 9,10-diethynylanthracene) yields solutions containing radical cations that exhibit characteristics of both oxidation of the diethynylaromatic portion of the bridge, and a mixed-valence state. The simultaneous population of bridge-oxidized and mixed-valence states is likely related to a number of factors, including orientation of the plane of the aromatic portion of the bridging ligand with respect to the metal d-orbitals of appropriate π-symmetry.

Geometric phase for collinear conical intersections. I. Geometric phase angle and vector potentials.

We present a method for properly treating collinear conical intersections in triatomic systems. The general vector potential (gauge theory) approach for including the geometric phase effects associated with collinear conical intersections in hyperspherical coordinates is presented. The current study develops an introductory method in the treatment of collinear conical intersections by using the phase angle method.

Potential energy surfaces for the 1 (4)A('), 2 (4)A(') 1 (4)A(") and 2 (4)A(") states of Li(3).

Global potential energy surfaces for the 1 (4)A('), 2 (4)A('), 1 (4)A("), and 2 (4)A(") spin-aligned states of Li(3) are constructed as sums of a diatomics-in-molecules (DIM) term plus a three-body term. The DIM model, using a large basis set of 15 (4)A(") and 22 (4)A(') states, is used to obtain a "mixed-pairwise additive" contribution to the potential. A global fit of the three-body terms conserves the accuracy of the ab initio points of a full configuration-interaction calculation.

New method for calculating bound states: the A(1) states of Li(3) on the spin-aligned Li(3)(1 (4)A(')) potential energy surface.

In this paper, we present a calculation for the bound states of A(1) symmetry on the spin-aligned Li(3)(1 (4)A(')) potential energy surface. We apply a mixture of discrete variable representation and distributed approximating functional methods to discretize the Hamiltonian. We also introduce a new method that significantly reduces the computational effort needed to determine the lowest eigenvalues and eigenvectors (bound state energies and wave functions of the full Hamiltonian).

General laser interaction theory in atom-diatom systems for both adiabatic and nonadiabatic cases.

This paper develops the general theory for laser fields interacting with bimolecular systems. In this study, we choose to use the multipolar gauge on the basis of gauge invariance. We consider both the adiabatic and nonadiabatic cases and find they produce similar interaction pictures.

Conical intersection between the lowest spin-aligned Li3(4A') potential-energy surfaces.

We have calculated new potential-energy surfaces for the lowest two spin-aligned (4)A(') states of the Li(3) trimer. This calculation shows a seam of conical intersections between these states resulting from the extra symmetry of the system when the atoms are in a collinear arrangement. This seam is especially important because of its proximity to the three-body dissociation limit of the system; ultracold scattering calculations and the bound-state energies of the system will be affected by the presence of this conical intersection.