  Recent three-dimensional, NLTE analyses of the solar spectrum have shown a
significant reduction in the C, N, O and Ne abundances leading to a Z/X ratio
of the order of 0.0177. We have computed solar models with this new mixture in
the OPAL opacity tables. The present He abundance we find seems rather
consistent with the helioseismic value. However, the convective envelope is too
shallow, and diffusion, even if it reduces the discrepancy, is not able to give
the current value. We present some numerical experiments consisting in changing
the diffusion velocities and/or the value of opacity at the base of the
convective envelope.
