The convergence of the lowest eigenvalue of a real nearly-symmetric matrix

The lowest eigenvalue of a real nearly-symmetric matrix is expressed as a perturbation series in terms of the eigenvalues of the symmetric part and the matrix elements of the skew-symmetric part. It is shown that the resulting series is closely related to the perturbation series for the lowest eigenvalue of a related hermitian matrix. This enables the behaviour of the lowest eigenvalue of a nearly symmetric matrix as the dimension of the matrix is increased to be deduced from the behaviour of the lowest eigenvalue of a hermitian matrix. This is of considerable importance as the behaviour of the lowest eigenvalue of a hermitian matrix as the dimension of the matrix is increased can be much more readily established. A possible application to Boys' transcorrelated method of calculating atomic and molecular energies is suggested.     

A comparison of gas-phase,plasma, sputtering and beam-foil excitations

A comparison of relative populations of ZnI and ZnII levels excited in equilibrium plasma, sputtering, gas-phase single collision, and beam foil sources is presented, and includes data on the first reported excitation studies under single collision conditions for a (transition metal atom)-(transition metal ion) interaction. A search for continuum emission from atomic chromium, like that seen during sputtering of chromium metal, produced a negative result.     

Differential scattering and rotational excitation in low-energy positron-hydrogen-molecule collisions

Differential cross sections are calculated for positron-hydrogen-molecule scattering below the positronium formation threshold usingK-matrix elements obtained by the Kohn variational method. The internuclear separation of the hydrogen molecule is fixed at its equilibrium value, 1.4a₀. The trial function used in the Kohn calculation is very flexible. It contains separable and Hylleraas-type basis functions and also basis functions to take into account longrange polarization. The cross sections for rotational excitation are also calculated, using the adiabatic-rotation approximation. Preliminary results are presented in this paper; full details will be published elsewhere.     

Colored electrically conducting polymers from furan,pyrrole, and thiophene

Furan, pyrrole, and thiophene were polymerized under catalysis by trichloro- and trifluoroacetic acid to produce colored polymers which were characterized by various methods, including electronic and proton magnetic resonance spectra and electrical conductances of deeply colored trichloroacetic acid adducts. The predominant repeat units of these polymers are of the same type as those of deeply colored cyclopentadiene polymers, except that a CH₂ group is replaced by O, NH, or S.     

A new theoretical approach to resonant dtµ formation

A key process in the muon-catalysed fusion cycle is a low-energy collision of tµ with a D₂ molecule which leads, at appropriate incident energies, to the formation of a resonant complex containing dtµ. In this paper the result is described of a formal derivation of the partial wave cross section for resonant dtµ formation, which makes use of elements of Feshbach's treatment of resonances. The expression obtained is similar to the Breit-Wigner formula. Full details of the calculation will be published elsewhere.