Behaviour of wavepackets of the 'Dirac oscillator': Dirac representation versus Foldy - Wouthuysen representation

The behaviour of wavepackets of the `Dirac oscillator' in (1 + 1) dimensions is examined. The Dirac oscillator is a relativistic extension of the harmonic oscillator. We construct a wavepacket in the usual Dirac representation and another one in the Foldy - Wouthuysen (FW) representation. In the nonrelativistic limit, these wavepackets are both reduced to Schrödinger's coherent wavepacket for the harmonic oscillator. The wavepacket in the Dirac …