The paper presents a numerical approach for the calculation of thermodynamics and spin correlations for spin-½ XY chains. To illustrate the approach we performed exact finite-chain calculations of all time-dependent two-spin correlation functions for the spin-½ Ising chain in the transverse field. The computed correlation functions permit to evaluate the frequency-dependent susceptibilities and structure factors for this model. The obtained results are discussed in detail. They may have an application for the interpretation of dynamic experiments on quasi-one-dimensional crystals that can be treated within the frames of the spin-½ transverse Ising model.