VARIATIONAL MONTE-CARLO CALCULATION OF THE SPIN GAP IN THE NU=1 QUANTUM HALL LIQUID

A variational method of calculating the spin 1 excitation energies of the v=1 quantum Wall liquid is presented in detail. We are able to inc lude Landau-level mixing and finite-thickness effects. The many-body w ave functions of the states near v=1 filling are taken to be a product of a lowest-Landau-level Laughlin-type wave function and a Jastrow fa ctor. A significant reduction in the calculated spin gap is found due both to Landau-level mixing (similar to 40% at r(s)=1) and to the effe ct of the finite thickness of the liquid (a further similar to 30% at r(s)=1). We find our calculations to be consistent with recent photolu minescence experiments in delta-doped samples.