Electron correlation effects in cobalt fluorides CoFn

The molecular cobalt fluorides CoF2, CoF3 and CoF4 are studied and compared by employing different basis sets as well as Quantum Information Theory (QIT) to investigate their correlation effects. These prototypical monomers may be systematically extended in size yielding a novel quasi 1‐dimensional, strongly correlated model system consisting of cobalt atoms bridged by oxygen atoms and fluorine termination on both ends. Accurate correlation energies are obtained using Full Configuration Interaction (FCI) and Full Configuration Interaction Quantum Monte Carlo (FCIQMC) calculations and the results are compared to Coupled Cluster and Density Matrix Renormalization Group (DMRG) energies. The analysis indicates the cobalt atom requires a larger number of one‐electron basis functions than fluorine and the use of localized molecular orbitals may facilitate calculations for the extended systems

A Hartree-Fock ab initio band-structure calculation employing Wannier-type orbitals

An ab initio Wannier-function-based approach to electronic ground-state calculations for crystalline solids is outlined. In the framework of the linear combination of atomic orbitals method the infinite character of the solid is rigorously taken into account. The Hartree-Fock ground-state energy, cohesive energy, lattice constant and bulk modulus are calculated in a fully ab initio manner as it is demonstrated for sodium chloride, NaCl, using basis sets close to the Hartree-Fock limit. It is demonstrated that the Hartree-Fock band-structure can easily be recovered with the current approach and agrees with the one obtained from a more conventional Bloch-orbital-based calculation. It is argued that the advantage of the present approach lies in its capability to include electron correlation effects for crystalline insulators by means of well-established quantum chemical procedures.Comment: 15 Pages, LaTex, 1 postscript figure (included), to appear in Chem. Phys. Letters (1998

Effects of Flat Tax Reforms in Western Europe on Income Distribution and Work Incentives

The flat income tax has become increasingly popular recently, yet its implementation is limited to Eastern Europe. We analyse the distributional and efficiency effects of flat tax scenarios for Western European countries. Our simulations show that flat tax rates required to attain revenue neutrality with existing basic allowances improve labour supply incentives. However, they result in higher inequality and polarisation. Flat rates necessary to keep the inequality levels unchanged allow for some scope for flat taxes to increase both equity and efficiency. Our analysis suggests that Mediterranean countries are more likely to benefit from flat taxes.flat tax reform, income distribution, work incentives, microsimulation

Simple Online and Realtime Tracking with a Deep Association Metric

Simple Online and Realtime Tracking (SORT) is a pragmatic approach to multiple object tracking with a focus on simple, effective algorithms. In this paper, we integrate appearance information to improve the performance of SORT. Due to this extension we are able to track objects through longer periods of occlusions, effectively reducing the number of identity switches. In spirit of the original framework we place much of the computational complexity into an offline pre-training stage where we learn a deep association metric on a large-scale person re-identification dataset. During online application, we establish measurement-to-track associations using nearest neighbor queries in visual appearance space. Experimental evaluation shows that our extensions reduce the number of identity switches by 45%, achieving overall competitive performance at high frame rates.Comment: 5 pages, 1 figur

Ab-Initio Calculation of the Metal-Insulator Transition in Sodium rings and chains and in mixed Sodium-Lithium systems

We study how the Mott metal-insulator transition (MIT) is influenced when we deal with electrons with different angular momenta. For lithium we found an essential effect when we include $p$-orbitals in the description of the Hilbert space. We apply quantum-chemical methods to sodium rings and chains in order to investigate the analogue of a MIT, and how it is influenced by periodic and open boundaries. By changing the interatomic distance we analyse the character of the many-body wavefunction and the charge gap. In the second part we mimic a behaviour found in the ionic Hubbard model, where a transition from a band to a Mott insulator occurs. For that purpose we perform calculations for mixed sodium-lithium rings. In addition, we examine the question of bond alternation for the pure sodium system and the mixed sodium-lithium system, in order to determine under which conditions a Peierls distortion occurs.Comment: 8 pages, 7 figures, accepted Eur. J. Phys.