The existence of phase-invariant solutions for a class of nonlinear wave-wave interacting systems is studied. These solutions have the property that the phase of each wave is invariant with time or unaffected by the nonlinear interactions. Explicit results are obtained for certain two-wave and...

The electron gas neutralized by a rigid positive background and in a quantizing magnetic field, is studied in a ‘quasi-classical’ model previously proposed by the author and collaborators. The plasma oscillation of the electron gas shows an acoustic-type dispersion for small wave vector. The...

The transition from dynamical (regular) to stochastical behaviour in nonlinear quantum systems is considered. A method of describing the stochastical instability is proposed for quantum systems. The method is based on the determination of a discrete time mapping of the creation and annihilation...

We have studied the radial distribution function and the second virial coefficient of interacting bosons. The second virial coefficient has been deduced theoretically and is in good agreement with experimental values. The third virial coefficient has been calculated from the experimental values...

The Poincaré cycles of some sharply localized initial excitations of the homogeneous linear chain of oscillators are studied, as well as the recurrence properties of the time-dependent autocorrelation functions of the phase space variables. In both cases a lower limit to the recurrence time is...

It is shown that the method of Van Leeuwen1,2) and Nauenberg and Nienhuis3) in the application of the renormalization theory to Ising-like spin systems, can easily be extended to include all one-dimensional classical spin systems with nearest neighbor interactions. The series for the free energy...

A molecular dynamics simulation of a rough sphere fluid with variable roughness is presented from which the intermediate scattering function, orientational correlation functions and velocity autocorrelation functions are calculated for several values of the density, roughness and wave number....

Results on the spectral shape of the collision-induced scattering (CIS) of CF4 gas are obtained for densities up to 270 amagats (296 K). For low frequencies they are compared with dipole-induced dipole theory; for high frequencies a short distance-induced binary collision model describes the...

The transport coefficients of a multicomponent gas mixture are approximated by means of a variational technique. It is shown that the procedure is equivalent to a more heuristic method developed earlier.

The influence of dipolar forces on the critical dynamics of ferro and antiferomagnets above the critical temperature is considered. The relaxation rates of the spin autocorrelation functions are calculated through the mode-mode coupling approach. They agree with Riedel and Wegner's dynamic...