In spite of persistent efforts, the problem of calculating the quantum time evolution of a wave-function or density matrix in a multidimensional Hamiltonian remains unsolved. Recent work has revolved around methods based on mean field, quantum-classical, or semiclassical ideas. The most rigorous of these approaches, semiclassical evolution with the Van Vleck propagator, is often highly accurate...

The study of the asymptotic behavior of nonautonomous linear systems arising from linearization around chaotic orbits offers good prospects for understanding complex nonlinear dynamics. Knowledge of the Lyapunov exponents (and other stability spectra) plays a central role in this context and several computational techniques have been established to address the problem in finite dimension, i.e. ...

We present a rigorous derivation of a semiclassical propagator for anticommuting (fermionic) degrees of freedom, starting from an exact representation in terms of Grassmann variables. As a key feature of our approach the anticommuting variables are integrated out exactly, and an exact path integral representation of the fermionic propagator in terms of commuting variables is constructed. Since ...

A new variation of the second-order generalized van Vleck perturbation theory (GVVPT2) for molecular electronic structure is suggested. In contrast to the established procedure, in which CASSCF or MCSCF orbitals are first obtained and subsequently used to define a many-electron model (or reference) space, the use of an orbital space obtained from the local density approximation (LDA) variant of...

Dirac semimetals show nontrivial physical properties and can host exotic quantum states like Weyl topological insulators under suitable external conditions. Here, by combining angle-resolved photoemission spectroscopy measurements (ARPES) first-principle calculations, we demonstrate that the Zintl-phase compound ${\mathrm{SmMg}}_{2}{\mathrm{Bi}}_{2}$ is in close proximity to a semimetallic stat...

Abstract All our observations that characterise space and time are expressed in terms of non-local, bi-tensorial objects such as geodesic intervals between events two-point (Green) functions. In this contribution, I highlight the importance characterising spacetime geome-try non-local objects, focusing particularly on two important bi-tensors play a particular fundamental role – Synge’s World f...

A primary goal at the interface of theoretical and experimental quantum magnetism is investigation exotic spin states, most notably liquids (QSLs). Magnetic rare-earth ions go beyond straightforward paradigm geometrical frustration in Heisenberg antiferromagnets by introducing competing energy scales, particular their strong spin-orbit coupling creates multiple split crystal electric-field (CEF...

The regression of daughter on dam first-lactation milk deviations from herd-mate averages was found to be linear from an analysis of 47,400 Holstein pairs. The linear equation was y=-25 .6 + .210 (x -27.6) and the quadratic equation was y-----25.6 + .208 (x -27.6) + .0000222 (x~-44131.4) with correlation coefficients, .18258 and .18268, respectively. These results suggest that selection respons...

INTRODUCTION The discovery of the deep freezing method of cattle semen preservation allowed for a worldwide exchange of genetic material and that the importation of semen from improved breeds have been often used in attempts to increase local livestock productivity. Frequently, this has been done without systematic evaluation of the introduced stocks in the new environment. In 1998, Argentina s...