We develop a field theoretical formalism for describing the non-linear dynamics of interacting nuclear, atomic and molecular species. Specifically, four simple types of reaction are considered all of which involve up to two reactants and two products. The equations of motion for space- and...

A second quantised operator approach has been used to calculate formulae for one-body fractional parentage coefficients (fpc) for a system of many spinless bosons. A number of examples have been discussed and compared with some of those already calculated by a different technique when used to...

A method is described for calculating crystal fields for rare-earth ions in non-magnetic hosts. Screening is included by performing a Bohm-Pines-like unitary transformation on the starting Hamiltonian which contains kinetic-energy and Coulombic energies of electrons in the presence of fixed...

The equivalent operator method has been extended and applied to anisotropic intersite electron-electron interactions between a central paramagnetic ion and its ligand neighbours. The relativistic character of both the interaction operator, in Breit-Pauli form, as well as the electronic...

The cyto-architecture of eukaryotic cells contains self-assembled long cylinder-like structures called microtubules (MTs) which play an important role in a number of cellular activities such as cell division, motility, information processing and intracellular transport. In this paper we present...

The Gross–Pitaevskii régime of a Bose–Einstein condensate is investigated using a fully non-linear approach. The confining potential first adopted is that of a linear ramp. An infinite class of new analytical solutions of this linear ramp potential approximation to the Gross–Pitaevskii...

A re-examination has been made of the form and the role of equivalent operators which are used to represent the effects of intersite electron-electron interactions. The approach takes into account the relativistic character of both the interaction operator and the electronic wavefunctions. The...

In this paper we discuss the various approaches to the problem of off-diagonal operators in atomic and nuclear physics. Most of these approaches have been based on the Schwinger algebra. Here, we propose a different way of incorporating generators of transitions between configurations. This is a...

The Hamiltonian of the Ising model in one-, two- and three-dimensions has been analysed using unitary transformations and combinatorics. We have been able to obtain closed formulas for the eigenvalues of the Ising Hamiltonian for an arbitrary number of dimensions and sites. Although the solution...

Coefficients of fractional parentage, which arise in the calculation of “crystal fields” in metals, have been calculated explicitly and compared with an earlier study where they were left undetermined but specific assumptions were made about them to reach conclusions about the “crystal...