WAVEFUNCTIONS OF 2-PARTICLE COLLECTIVE EXCITATIONS

A formalism is developed by which the wavefunctions, as well as the energies, of two-particle collective excitations may be obtained using the corresponding two-particle Green function. Using a simple one-dimensional model of a polyene chain, the wavefunction of an excitonic state is calculated. This calculation shows that the electron and hole are closely bound. A similar calculation is performed for the spin-wave mode in antiferromagnetic gamma manganese.