STRUCTURE AND PROPERTIES OF MD SIMULATED NA2O.SIO2 MELT COMPARISON OF THE BORN-MAYER-HUGGINS AND PAULING INTERIONIC POTENTIALS

MD simulations of Na2O.SiO2 melt were performed using Born-Mayer-Huggins and Pauling pair potential functions in the temperature range of 1000-2000 K. Thermodynamic properties as total energy, pressure and heat capacity were compared for the two simulated systems as well as their structural characteristics. Thermodynamic behaviour of both systems is similar and the calculated values of the heat capacity are close to the experimental one. There are some differences between the simulated structures: Born-Mayer-Huggins pair potential functions support occurence of some silicon atoms coordinated by five oxygens and more branched structure of silicate polyanions with many rather small rings. On the other hand, the structure simulated using Pauling pair potential functions has more chain-like character with few large rings and there are no 5-coordinated silicon atoms present.