Cosmological ( \Lambda CDM ) TreeSPH simulations of the formation and evolution of galaxy groups and clusters have been performed .
The simulations invoke star formation , chemical evolution with non-instantaneous recycling , metallicity dependent radiative cooling , strong star-burst , and ( optionally ) AGN , driven galactic super-winds , effects of a meta-galactic UV field and thermal conduction .
Results for two clusters , one Virgo-like ( T \simeq 3 keV ) and one ( sub ) Coma-like ( T \simeq 6 keV ) , are presented .
At z =0 the stellar contents of both clusters consist of a central dominant ( cD ) galaxy surrounded by cluster galaxies and intracluster stars .
The intracluster ( IC ) stars are found to contribute 20-40 % of the total cluster B-band luminosity at z =0 and to form at a mean redshift \bar { z } _ { f } \sim 3 being on average about 0.5 Gyr older than the stars in cluster galaxies .
UBVRIJHK surface brightness profiles of the IC star populations are presented ; the profile of the larger cluster matches the observed V-band profile of the cD in Abell 1413 ( T \simeq 8 keV ) quite well .
The typical colour of the IC stellar population is B-R=1.4-1.5 , comparable to the colour of sub- L ^ { * } E and S0 galaxies .
The mean Iron abundance of the IC stars is about solar in the central part of the cluster ( r \sim 100 kpc ) decreasing to about half solar at the virial radius .
The IC stars are \alpha -element enhanced with a weak trend of [ O/Fe ] increasing with r and an overall [ O/Fe ] \sim 0.4 dex , indicative of dominant enrichment from type II supernovæ .

The IC stars are kinematically significantly colder than the cluster galaxies : The velocity dispersions of the IC stars are in the inner parts of the clusters ( r \sim 100-500 kpc ) only about half of those of the cluster galaxies increasing slightly outward to about 70 % at r =1-2 Mpc .
The typical projected velocity dispersion in the Virgo-like cluster at R \ga 50 kpc is 300-600 km/s depending on orientation and projected distance from the cluster center .
Rotation is found to be dynamically insignificant for the IC stars .
The velocity distributions of IC stars and clusters galaxies are in one cluster highly radially anisotropic , in the other close to isotropic .