In order to analyse the behavior of molar volume evolution in time of ZnO rocksalt structure under extended pressure and temperature; we investigate parallel molecular dynamics and DL_Poly_4 software on RAAVEN supercomputer of Cardiff University (UK). We use the range of temperature 300-3000K and 0-100GPa for 5832 atoms of ZnO. The interatomic interactions are modeled by Buckingham-Coulomb potential. Although no more data available under previous conditions, our work is in vicinity of theoretical and experimental information. These results have great importance especially in Nanotechnology.