A Latin square is pan-Hamiltonian if every pair of rows forms a single cycle. Such squares are related to perfect 1-factorisations of the complete bipartite graph. A square is atomic if every conjugate is pan-Hamiltonian. These squares are indivisible in a strong sense – they have no proper subrectangles. We give some existence results and a catalogue for small orders. In the process we identif...

Electron correlation effects in Fe are analysed using a first-principles linear combination of atomic orbitals scheme. In our approach, we first use a local orbital density functional solution to introduce a Hubbard Hamiltonian without fitting parameters. In a second step, we introduce a many-body solution to this Hamiltonian using a dynamical mean-field approximation. Our analysis shows that m...

Quantum mechanical phases arising from a periodically varying Hamiltonian are considered. These phases are derived from the eigenvalues of a stationary, “dressed” Hamiltonian that is able to treat internal atomic or molecular structure in addition to the time variation. In the limit of an adiabatic time variation, the usual Berry phase is recovered. For more rapid variation, nonadiabatic correc...

In this expression ↠and â denote the creation and annihilation operators of the one-mode radiation field of frequency Ω, ωA the separation between the atomic levels, Ĵz denotes a collective atomic operator which counts the difference of population between the two atomic levels, Ĵ+ a collective atomic operator which promotes atoms from the lower level to the upper level, Ĵ− = Ĵ † +, and μ stan...

A review of electromagnetically induced transparency is given. A semiclassical Hamiltonian is used to show that atomic coherence can inhibit absorption and enhance dispersion in the adiabatic limit. Experimental demonstrations and applications are discussed. The nonadiabatic effects are derived in the c-number Langevin formalism, and shown to give rise to correlate the phase of two incident fie...

We evaluate all the electron-phonon couplings derived from the one-body electronic interactions, in both the adiabatic and extreme non-adiabatic limit, for a dimer with a non-degenerate orbital built from atomic wave functions of Gaussian shape. We find largely different values of the coupling parameters in the two cases, as well as different expressions of the corresponding terms in the Hamilt...

A generic procedure is proposed to construct many-body quantum Hamiltonians with partial dynamical symmetry. It is based on a tensor decomposition of the Hamiltonian and allows the construction of a hierarchy of interactions that have selected classes of solvable states. The method is illustrated in the SO(6) limit of the interacting boson model of atomic nuclei and applied to the nucleus 196Pt.

Expressions for the effective Quantum Electrodynamics (QED) Hamiltonian due to self-energy screening (self-energy correction to the electron-electron interaction) are presented. We use the method of the two-time Green’s function, which handles quasidegenerate atomic states. From these expression one can evaluate energy corrections to, e.g., 1s2p 3P1 and 1s2p 1P1 in helium and twoelectron ions, ...