CROSSOVER BETWEEN WEAK AND STRONG-COUPLING IN 2D SUPERCONDUCTORS

We study the crossover between weak coupling and strong coupling in tw o-dimensional (2D) superconductors at T not equal 0 in the weak coupli ng regime, described by the BCS state, and we calculate the order para meter and the chemical potential at T=0 and T not equal 0 for the mode l of a 2D superconductor. In the strong coupling regime the energy exc itation has the scale of the pairs generated by the attractive interac tion. The order parameter and the chemical potential at T not equal 0 are calculated, and we show that there is a continuous transition betw een the two regimes.