Ehrenfest ‘phase-space’ trajectories and quantum chaos in He atom under strong,oscillating magnetic fields: an application of time-dependent quantum fluid density functional theory (TDQFDFT)

Using a dynamical signature proposed earlier from our laboratory, quantum chaos in He atom interacting with strong, oscillating magnetic fields has been studied through a comparison between the nonlinear divergence of two neighbouring Ehrenfest ‘phase-space’ (EPS) trajectories differing slightly in initial conditions and the Loschmidt echo. The dynamical EPS signature can detect quantum chaos independently of the Loschmidt echo and in agreement with the latter, even for low-lying states, in the same spirit as that of classical chaos. This time-dependent signature extends the concept of quantum chaos to systems which have no classical counterparts and brings the concept of quantum chaos closer to that of classical chaos.     

The phosphorescent triplet state of p-xylene in an isotopically mixed crystal at 1·2K: an investigation by E.S.R. and MIDP

The phosphorescence spectrum of p-xylene-h ₁₀ in a p-xylene-d ₁₀ host is first presented. Secondly we report E.S.R. experiments performed on p-xylene-α,α′-d ₆ in p-xylene-d ₁₀; from an analysis of the orientations of the principal axes in combination with the crystal structure and of the hyperfine splittings it is concluded that the in-plane principal axes of the zfs tensor make an angle of 68° with the molecular axes. Thirdly we discuss Microwave-Induced Delayed Phosphorescence (MIDP) experiments on p-xylene-h ₁₀ in p-xylene-d ₁₀ in which the relative radiative rate constants for decay from the zero-field spin components of the triplet state to single vibronic bands of the ground state have been obtained.

The results of the MIDP and E.S.R. measurements are shown to be mutually consistent in terms of a model in which the effect of the crystal field and the methyl substituents on the pseudo-Jahn-Teller unstable electronic structure of the triplet state of benzene is described.     

SU(2) ×U(1) Gauge theory of bosonic and fermionic fields inS 3 ×R space-time

The tetradic Lorentz-gauge invariant formulation of the SU(2) × U(1) theory in S³ × R space-time is presented and the general gauge covariant Dirac-Klein-Gordon-Maxwell-Yang-Mills equations are derived. A direct comparison of these equations to those of the SU(2) × U(1) gauge theory on Minkowskian background points out major differences effectively induced by the minimally coupling to S³ × R gravity.     

The perihelion of Mercury advance and the light bending calculated in (enhanced) Newton’s theory

Quantum fluctuations of a real massless scalar field are studied in the context of the generalized uncertainty principle (GUP). The dynamical finite vacuum energy is found in spatially flat Friedmann–Robertson–Walker spacetime which can be identified as dark energy to explain late time cosmic speed-up. The results show that a tiny deviation from the standard uncertainty principle is necessary on cosmological ground. By using the observational data we have constraint the GUP parameter even more stronger than ever.     

Comment on ‘structure of α-Fe2O3 single crystal surfaces following Ar+ ion bombardment and annealing in O2’ by R.J. Lad and V.E. Henrich

A recent paper by Lad and Henrich [Surface Sci. 193 (1988) 81], on the phase changes induced by Ar⁺ bombardment and annealing in O₂ at Fe₂O₃ single crystal surfaces, is commented upon. It is pointed out that quantitative XPS analysis would have provided more direct information on phase changes induced by surface treatments. It is suggested that chemical effects contribute to the O 1s spectrum asymmetry observed in Ar⁺ bombarded Fe₂O₃ surfaces.