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to calculate realistic models of chemically peculiar stars we have used a 1-d , lte , hydrostatic model atmosphere code llmodels ( shulyak .
this code allows one to treat the line opacity without simplifying approximations and in this way accurately estimate how modification of the line opacity due to anomalous abundances , chemical stratification or the presence of strong magnetic field affects stellar atmospheres .
our calculations cover the @xmath0 range between 6500 and 18000  k with a step of 250500  k and the @xmath1 range of 3.254.5  dex with a step of 0.25  dex . for @xmath2 models
we have performed additional calculations for 5  kg magnetic field using the method described by kochukhov et al .
( @xcite ) .
individual abundances of 41 elements were adopted based on the results of modern chemical composition analyses of the srcreu and si - type cp stars . for ca , si , cr ,
fe and several other elements we include empirical temperature dependence of the element concentrations ( ryabchikova @xcite ) .
the line lists are extracted from the vald database ( kupka et al .
the ap - star model grid is complemented with the solar composition models , calculated for an extended range of atmospheric parameters ( 600020000  k in @xmath0 and 2.54.5  dex in @xmath1 ) .
k and @xmath2 . the @xmath3-@xmath4 relations ( left panel ) and flux distributions ( right panel )
are presented for the models with solar abundances and the ap - star abundance table.,width=453 ]    for each ap - star model atmosphere we have examined deviation of the temperature stratification , flux distribution , hydrogen line profiles and photometric colors from those of normal composition model with the same parameters .
[ fig1 ] illustrates the impact of anomalous abundances on the atmospheric structure of an early - a star . in general , we find that + ( i ) peculiar abundances lead to 200400  k increase of @xmath3 in deep layers and 100200  k cooling of the upper atmosphere ; + ( ii ) the impact of 5  kg magnetic field is negligible compared to that of the chemical composition anomalies ; + ( iii ) fitting normal composition models to the hydrogen lines of ap stars underestimates @xmath0 by @xmath5250  k and @xmath1 by @xmath50.25  dex ; + ( iv ) model fluxes of ap stars are dominated by the energy redistribution from uv to visual and ir wavelengths ; the bolometric corrections of ap and normal stars differ systematically by @xmath6  mag ; + ( v ) usual photometric calibrations overestimate @xmath0 of ap stars by 300500  k.      kochukhov , o. , khan , s. , shulyak , d. : 2005 , _ astron . &
_ * 433 * , 671 kupka , f. , piskunov , n. , ryabchikova , t.a . ,
stempels , h.c . ,
weiss , w.w . : 1999 , _ astron .
& astrophys .
ser . _ * 138 * , 119 ryabchikova , t. : 2005 , _ astron .
letters _ * 31 * , 388 shulyak , s. , tsymbal , v. , ryabchikova , t. , sttz , c. , weiss , w.w . : 2004 , _ astron . &
_ * 428 * , 993
the atmospheric structure of chemically peculiar stars deviates from that of normal stars with similar fundamental parameters due to unusual chemistry , abundance inhomogeneities and the presence of strong magnetic field . 
 these effects are not considered in the standard model atmospheres , possibly leading to large errors in the stellar parameter determination and abundance analysis . to tackle this problem we used the state - of - the - art opacity sampling model atmosphere code llmodels to calculate comprehensive grid of new generation model atmospheres for magnetic cp stars . 
 this grid covers the whole parameter space occupied by srcreu and si - peculiar stars , taking into account characteristic temperature dependence of the chemical abundances . here 
 we present the first results of our model atmosphere calculations .