Density functional theory(DFT) calculations were performed for PATO and its derivatives.B3LYP and B3P86 functionals with 6-31+G** basis set were used.Vibrational analyses show that the optimized structures have no imaginary frequencies.Heats of formation(HOFs) for PATO derivatives in gas phase are also determined both at two levels using isodesmic work reactions.A good liner equation: ΔfHθ(B3P86)=-40.978 98+0.984 65×ΔfHθ(B3LYP) is obtained from the calculated accurately values between the two levels.It indicates that designing isodesmic work reactions and calculation accuracy is reliable and feasible.Thermal stabilities are evaluated via bond dissociation energies(BDEs) of the weakest C-NO2 and the biggest Mulliken charges of nitro group in PATO derivatives

and two liner equations are extrapolated: BDEC-NO2=273.022 54-52.210 49×(qNO2)

BDEC-NO2=-67.148 21-1432.307 69×(qNO2).The relative stability of PATO derivatives is illustrated according to the results calculated by HOFs

C-NO2 bond dissociation energy and Mulliken charge of nitro group(qNO2).The obtained results provide basic data and regularity for the molecular design of new type of high energetic density materials.