With replacement of N atoms by CH groups in the most stable cycled N4H4 molecules,twelve possible isomers of Nn(CH)4-nH4 have been designed and optimized at the B3LYP/6-311++G level of theory.The vibrational frequencies were calculated at the same level of theory.The structures and properties were analyzed with the natural bond orbital(NBO) and the atoms in molecules(AIM)theory.Meanwhile,the dipole moments and the energy have been discussed.The results indicate that stabilities of these isomers increase with more CH groups replacements of N4H4 due to decrements of their densities of energies.The G3B3 calculations show that the isomers have high heat of formations(HOFs)and higher density of energies,which indicate them maybe a kind of potential and novel energetic material.
