Excitations and phase segregation in a two component Bose-Einstein condensate

Bogoliubov-de Gennes (BdG) equations and the excitation spectrum of a twocomponent Bose-Einstein condensate (BEC) are derived with an arbitrary interaction between bosons, including long-range and short range forces. The nonconverting BEC mixture segregates into two phases for some two-body interactions. Gross-Pitaevskii (GP) equations are solved for the phase segregated BEC. A possibility of boundary-surface and other localised excitations is studied.