Globular Clusters (GCs) are generally treated as natural validators of simple stellar population (SSP) models. However, there are still some differences between real GCs and SSPs. In this work we use a direct N-body simulation code Nbody6 to study the influences of dynamical interactions, metallicity and primordial binaries on Milky Way globular clusters’integrated properties. Our models start with N = 100, 000 stars, covering a metallicity range Z = 0.0001 ? 0.02, Stellar evolution and external tidal field representative for an average Milky Way GC are taken into consideration. A subset of our models contain primordial binaries, resulting in a binary fraction as currently observed at a model age of GCs. The integrated colours and Lick indices are calculated using BaSeL and Bluered stellar spectral libraries separately. By including dynamical interactions, our model clusters show integrated features (colours become slightly bluer, Hβ up to 0.1?A greater and [MgFe]′ 0.05?A smaller) making the clusters appear slightly younger than the model clusters without dynamical interactions. This effect is caused mainly by the preferential loss of low-mass stars which have a stronger contribution to redder passbands as well as different spectral features compared to higher-mass stars. In addition, this effect is larger at lower metallicities. On the contrary, the incorporation of primordial binaries reduces this effect.
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