Study On Energy Limitation And High-density Construction Strategy Of Energetic Molecules

The energy of energetic materials determines the limitation of the performance of weapons and equipment.For a long time,designing and developing higher-energy molecules is the focus of energetic materials research,and the energy limitation of energetic materials needs more attention.It is of great significance for the design of high-energy molecules.In this paper,the limitation of energy and high density of CHNO energetic materials are studied,and the suitability of several calculation methods for formation enthalpy in high-throughput molecular design is evaluated.The main research contents are as follows:The energy of energetic material is a thermodynamic property,which is related to the energy of the reactants and products.In this paper,based on the basic principle of chemical bond energy,the bonding electron energy in chemical bond is defined to calculate the energy source of explosive products of energetic materials,and the energy equation is established to calculate its limitation of energy.This studies shown that the higher the energy of the bonding electron in a chemical bond,indicate the more molecule energy.N-N bond is the highest energy storage bond in energetic materials.Increasing N/C ratio and OB can effectively improve the energy of energetic materials,while O-H is the most unpopular group,because its bonding electron energy is the lowest,breaking O-H requires absorbing more energy,cg-N is the maxmium energetic compound in CHNO energetic materials.In addition,the limitation of energy of energetic materials without N atoms is studied,H atom is not the energetic favored,the maximum energy is-14.09 and-15.03 k J/g with and without tension,respectively.High packing density( d_c)is of great importance in the field of energetic materials,as it is positively correlated with the energy,which refers to power,detonation property,or specific kinetic energy of cylinder.It makes the high d_c a focus in designing new energetic molecules.This article systematically analyzes the composition,molecular topology,intermolecular interaction,molecule density( d_m)and packing coefficient(PC)of top 36highest d_c(?1.90 g/cm~3)compounds consisting of C,H,N and O atoms extracted from CSD.For these compounds,a d_m-PC contradiction exists as the higher d_m,the lower PC.The absence of planar structure and strong hydrogen bonding acceptor or donor in high d_mmolecules is responsible for the low PC,and further the contradiction.Two ways are summarized as a strategy for achieving high d_c:one to design caged molecules with high oxygen balance,because they generally possess extraordinarily high d_mto remedy the shortcoming of a rather low PC;and the other is to design planar molecules with dense and strong hydrogen bonding acceptors and donors,thereby high PC based on moderate d_m,or high d_c,can be obtained.This work is expected to guide the design of new high-energy compounds.The performance prediction methods for high-throughput energetic molecule design and screening are required to balance accuracy and efficiency.In the present work,the suitability of three common theoretical methods on different levels for heat of formation(HOF)prediction under the atomization scheme for high-throughput energetic molecule design and screening are evaluated,including semi-empirical PM6 method,density functional theory method B3LYP/6-31G(d,p)and high-precision complete basis set CBS-4 method.The solid HOF of twenty energetic molecules were compared,and the results of different theoretical levels were found to differ greatly.Based on the predicted HOF,experimental density and three models(K-J,BKW and VLW),the detonation performance of ten common energetic molecules were predicted.The results show that,B3LYP method possesses the best suitability and efficiency,and the predicted detonation performance is closed to that obtained by CBS method.For example,the average relative deviation of the detonation velocity and detonation pressure predicted by BKW are only 0.4%and 1.2%,respectively.However,both the low-precision PM6 method and the time-consuming CBS method are difficult to balance the requirements of precision and efficiency in high-throughput energetic molecules design and screening.It suggests that,for the high-throughput design of energetic molecules,a medium-precision method is adequate for rapid HOF prediction.In conclusion,by studying the energy limitation and high density of traditional CHNO energetic materials,a new strategy to improve energy and density is innovatively proposed,which is expected to guide the design of new high-energy compounds.