Context : On its asteroseismic side , the initial run of CoRoT was partly devoted to the solar like star HD49933 .
The eigenmodes of this F dwarf have been observed with unprecedented accuracy .

Aims : We investigate quantitatively the impact of changes in the modeling parameters like mass and composition .
More importantly we investigate how a sophisticated physics affects the seismological picture of HD49933 .
We consider the effects of diffusion , rotation and the changes in convection efficiency .

Methods : We use the CESAM stellar evolution code coupled to the ADIPLS adiabatic pulsation package to build secular models and their associated oscillation frequencies .
We also exploited the hydrodynamical code STAGGER to perform surface convection calculations .
The seismic variables used in this work are : the large frequency separation , the derivative of the surface phase shift , and the eigenfrequencies \nu _ { \ell = 0 ,n = 14 } and \nu _ { \ell = 0 ,n = 27 } .

Results : Mass and uncertainties on the composition have much larger impacts on the seismic variables we consider than the rotation .
The derivative of the surface phase shift is a promising variable for the determination of the helium content .
The seismological variables of HD49933 are sensitive to the assumed solar composition and also to the presence of diffusion in the models .

Conclusions :