  Solar models computed with mass loss, microscopic diffusion of helium and
heavy elements and with updated physics have been evolved from the pre-main
sequence to present days; they are compared to the observational constraints
including lithium depletion and to the Solar Reference Model (SRM) of Basu et
al. (1996), derived by inversion. Microscopic diffusion significantly improves
the agreement with the observed solar frequencies and agree with the SRM within
+- 0.2% for the sound velocity and +- 1% for the density, but slightly worsens
the neutrino problem. Neither microscopic diffusion nor overshooting explain
the observed lithium depletion consistently with helioseismological
constraints, while a mass loss process does it. Models computed with OPAL
equation of state and opacities are in better agreement with the seimic sound
speed. To reach the level of precision of helioseismological observations the
accuracy of solar models still needs to be improved by one magnitude; any such
improvement will necessitate equation of state and opacity data taking into
account of detailed changes in the mixture.
