The authors have used an empirical tight-binding method to calculate the electronic band structure of the monolayer superlattice GaAs-Ga1-xAlxAs as a function of composition (0<x<1) and hydrostatic pressure (0-50 kbar). They found that this empirical tight-binding method with a d-3 rule determining the off-diagonal matrix elements gives more accurate results for the energy gaps of GaAs, AlAs at high hydrostatic pressure which they also applied in the superlattice calculation. They believe that pressure coefficients are characteristic of symmetry structures for not only compounds like GaAs but also superlattices, and can be used to discern the origin of states, which is especially useful and convenient at high hydrostatic pressure where crossing of states may occur.