We present high-quality numerical calculations of the exciton center-of-mas
s dispersion for GaAs/AlxGa1-xAs quantum wells of widths in the range 2-20
nm. The (k) over right arrow.(p) over right arrow coupling of the heavy- an
d light-hole bands is taken fully into account. An optimized center-of-mass
transformation enhances numerical convergence. We derive an easy-to-use se
mianalytical expression for the exciton ground-state mass from an ansatz fo
r the exciton wave function at a finite momentum. It is checked against the
numerical results and found to give very good results. We also show multib
and calculations of the exciton ground-state dispersion using a finite-diff
erence scheme in real space, which can be applied to rather general heteros
tructures.