Résumé
Solar models are presented, which include the new treatment of the diffusion-circulation coupling as discussed for halo stars by Vauclair (1999) and Theado & Vauclair (2000) and the new European Nuclear Astrophysics Compilation of REaction rates (Angulo et al. 1999) It has been known for several years (cf Richard et al. 1996) that the mixing processes below the solar convection zone must be limited to a small depth, probably due to mu -gradient effects; this is necessary to account for the constancy of the He-3/He-4 ratios these last 3 Gyrs, as observed from lunar rocks; it is also consistent with helioseismic results. In previous works, a critical mu -gradient was arbitrarily introduced to stop the mixing processes at a given depth. In the present models, the physics of diffusion-induced mu -gradients and their coupling with macroscopic motions is discussed and more precisely introduced.