Molecular modelling is an appreciated tool that brings valuable data on physical and chemical characteristics of materials that eliminates the necessity of conducting any experiment. This method allows to calculate the performance of energetic molecules to be synthesized. In the work, the detonation parameters of the energetic organic compounds Pentaerythritol tetranitrate(PETN), Butanetriol trinitrate (BTTN), Trimetylolethane trinitrate (TMETN) and Diethyleneglycol dinitrate (DEGDN) has theoretically been calculated and some values compared with the literature values. Moreover, three hypothetical molecules combining PETN with other explosive molecules have been designed. The detonation properties have been calculated using density functional theory (DFT) with B3LYP/6-31G (d,p) basis set. It has been concluded that all molecules have the effect of increasing the explosion parameters of PETN.