Charge-transfer molecular dynamics simulations of NaY zeolite in thermodynamical equilibrium in the microcanonical ensemble were carried out in order to obtain the charge distribution of all charge-transferring species. The interaction potentials used were parameterised ab initio calculations and take into account the Al-O and Si-O partially covalent bonds, The different kinds of O and Si atoms are characterised based on their charge distributions which are comparable with experimental Si-29 MAS NMR data.