Multichannel spectrum of neutral particles trapped by a wire

The energy spectrum of a neutral atom bound in the magnetic field created by a straight line direct current is given by the Rydberg formula for particles with spin less than 3/2. An adiabatic representation leads to a natural understanding of this spectrum and provides a good approximation to the bound state energy levels. A more accurate finite element method is applied to directly solve the time-independent Schrodinger equation for neutral particles with arbitrary spin. A combination of the finite element method with multichannel quantum defect theory provides a more efficient method to calculate the bound state energies. In addition, new spectral features arise for particles with spin greater than 1.