Photospheric parameters and abundances are presented for a sample of single-lined chromospherically active binaries from a differential LTE analysis of high-resolution spectra .
Abundances have been derived for 13 chemical species , including several key elements such as Li , Mg , and Ca .
Two methods have been used .
The effective temperatures , surface gravities and microturbulent velocities were first derived from a fully self-consistent analysis of the spectra , whereby the temperature is determined from the excitation equilibrium of the Fe i lines .
The second approach relies on temperatures derived from the ( B - V ) colour index .
These two methods give broadly consistent results for the stars in our sample , suggesting that the neutral iron lines are formed under conditions close to LTE .
We discuss the reliability in the context of chromospherically active stars of various colour indices used as temperature indicators , and conclude that the ( V - R ) and ( V - I ) colours are likely to be significantly affected by activity processes .
Irrespective of the method used , our results indicate that the X-ray active binaries studied are not as metal poor as previously claimed , but are at most mildly iron-depleted relative to the Sun ( -0.41 \la { [ Fe / H ] } \la + 0.11 ) .
A significant overabundance of several chemical species is observed ( e.g. , the \alpha -synthezised elements ) .
These abundance patterns are discussed in relation to stellar activity .