Evaluation method of hygroscopicity of energetic materials under different temperature and humidity conditions

Abstract

The application discloses an evaluation method of hygroscopicity of energetic materials under different temperature and humidity conditions. The method is based on the water molecule density under various temperature and humidity conditions, and the hygroscopicity of various energetic molecules under arbitrary temperature and humidity conditions is evaluated by establishing an energetic molecule model and controlling the size of the system model, so that the method is not affected by external environmental factors and human factors. The simulation method is simple, safe and efficient. The experiment needs a long time from sample preparation to hygroscopicity characterization, and the simulation method can calculate the hygroscopicity of samples under multiple different conditions at the same time, so that the time for evaluating the hygroscopicity of energetic molecules is greatly saved.

Description

TECHNICAL FIELD

[0001] The present application relates to a method for evaluating the hygroscopicity of energetic materials under different temperature and humidity conditions, and belongs to the field of energetic materials. BACKGROUND

[0002] Energetic materials refer to materials capable of releasing a large amount of chemical energy in a chemical reaction process, which are widely used in explosives (propellants, explosives, propellants, pyrotechnic agents, etc.). The research on energetic materials includes both theoretical research and experimental research. At present, the research on energetic materials focuses on improving the energy density, stability, safety and environmental protection of energetic materials, etc. In the aspect of stability research, the hygroscopicity of materials is crucial for the evaluation of the stability of energetic materials, and is the key to long-term storage of energetic materials without reducing performance, maintaining good processing performance, safe and stable energy release, which directly affects the actual application performance of explosives.

[0003] Therefore, it is of great significance to evaluate the hygroscopicity of energetic materials. The evaluation method of hygroscopicity of energetic materials is usually carried out by experimental operation, such as the desiccator equilibrium method (GJB 770B-2005, Firework Test Method Method 404.1 Desiccator Equilibrium Method [S.]) and the dynamic adsorption method (WJ 20699-2018, Performance Test of Explosives and Propellants Hygroscopicity of Energetic Materials Dynamic Adsorption Method [S.]). The desiccator equilibrium method mainly places the pre-dried and weighed sample in the desiccator, adds a saturated solution of a specific salt in the desiccator, and places the desiccator containing the sample in a certain temperature to create a certain temperature and humidity environment. The sample mass change before and after hygroscopicity is tested by weighing the sample at a certain time, and the sample hygroscopicity is evaluated. Similarly, the dynamic adsorption method is also used to evaluate the hygroscopicity of the sample by experimental method, which is to pass a certain mass of air through a certain mass of sample at a certain temperature and humidity, and to obtain the hygroscopicity value of the sample according to the mass change of the sample. The two standards for evaluating hygroscopicity are both by experimental method, and the repeatability of each experiment is greatly affected by environmental and human factors. The sample hygroscopicity can only provide limited reference, and the test requires sample preparation, which consumes a lot of time. In foreign research, in addition to using the above weighing method, X-ray and scanning electron microscope and other microscopic characterization means are also widely used to analyze the hygroscopicity of the sample from a more microscopic angle. For example, Alexei V. Tivanski et al. ([Suman Ghorai, Alexei V. Tivanski. Hygroscopic Behavior of Individual Submicrometer Particles Studied by X-ray Spectromicroscopy [J]. Analytical Chemistry, 2010, 82(22), 9289-9298.]) used X-ray spectromicroscopy to study the hygroscopic behavior of individual submicrometer particles, and proposed a new application of scanning transmission X-ray microscopy (STXM) and near edge X-ray absorption fine structure (NEXAFS) spectroscopy for quantitative analysis of the hygroscopicity and phase transition of individual submicrometer particles. The method exposes the deposited single particle to water vapor at different relative humidities, and then performs STXM / NEXAFS spectroscopic microscopy analysis, which can provide quantitative information on the physical and chemical properties of the particles and how these properties change with relative humidity.Martin Ebert et al.([Martin Ebert, Marion Inerle-Hof, Stephan Weinbruch. Environmental scanning electron microscopy as a new technique to determine the hygroscopic behaviour of individual aerosol particles[J]. Atmospheric Environment, 2002, 36(39-40), 5909-5916.) from Germany used Environmental Scanning Electron Microscopy (ESEM) to study the hygroscopic behavior of particles in the range of 0.1-20 mm, which allowed in-situ observation of individual aerosol particles while changing the temperature and / or relative humidity of the sample chamber, the hygroscopic behavior of these particles (e.g., deliquescence, adsorption of water on the surface of the particles) could be directly observed, with a lateral resolution of 8-15 nm, the authors considered that the values obtained by ESEM were in good agreement with those found in the literature.

[0004] In summary, most of these evaluations of hygroscopicity are experimental studies, however, there are certain errors in the control of environmental temperature / humidity, so the data obtained by experiments will have volatility. There is no suitable model and method to better compare the hygroscopicity of energetic materials under different temperature and humidity conditions. If this method and technology can be broken through, it will bring great convenience to the anti-hygroscopicity research of energetic materials, and also can bring new theoretical guidance for us to test / evaluate the hygroscopicity of energetic materials. SUMMARY

[0005] In view of the problem that the strong hygroscopicity of energetic materials affects the long-term storage, efficient use and safety of the materials, the purpose of the present application is to provide a simple and efficient method for evaluating the hygroscopicity of energetic materials under different temperature and humidity conditions.

[0006] The technical solution of the present application is as follows: the method for evaluating the hygroscopicity of energetic materials under different temperature and humidity conditions provided by the present application specifically comprises the following steps:

[0007] In the first step, the standard cif file of the initial unit cell of the energetic molecule is imported into the Materials studio molecular simulation software, a certain size of energetic molecule cluster is constructed, and the constructed energetic molecule cluster is placed in a larger cubic lattice, the water molecules with known density under specific temperature and relative humidity conditions are multiplied by n times and filled into the space between the energetic molecule cluster and the cubic lattice, and an initial model is constructed.

[0008] Second step, the initial model is built to carry out NVT molecular dynamics calculation, the last frame model after completing the molecular dynamics calculation is taken out, and the structure optimization of the non-optimized unit cell is carried out by using Forcite module to eliminate the structural instability factors existing in the structure, and a stable model M after moisture absorption is obtained;

[0009] Third step, the stable model M after moisture absorption is decomposed, and the model M1 of the moisture absorbed water molecule and the model M2 of the single energetic molecular cluster are extracted respectively, and the system energy of the three models, i.e. the energy E water of M1, the energy E cluster of M2 and the energy E total of M, is calculated by using Forcite module, and finally the interaction energy E interaction of the energetic molecular cluster with water molecules under specific temperature and relative humidity conditions is obtained, and the moisture absorption of the energetic molecular cluster is evaluated by the interaction energy of the energetic molecular cluster with water molecules under different temperature and relative humidity conditions.

[0010] Preferably, in the first step, the energetic molecules include but are not limited to oxidizing agents, explosives, metal powders, hydrogen storage materials and any other moisture-absorbing energetic materials, the oxidizing agent can be ammonium perchlorate (AP), potassium perchlorate (KP), ammonium dinitramide (ADN), ammonium nitrate (AN) and the like as well as their eutectic crystals, mixed crystals and modified crystals; the explosive can be hexogen (RDX), octogen (HMX), hexanitrohexaazaisowurtzitane (CL-20), 1’1-dihydroxy-5,5’-tetrazolyl dihydroxylamine (TKX-50), 3,4-dinitro-3,4-oxo furazan (DNTF), all-nitrogen / multi-nitrogen energetic materials and the like as well as their eutectic crystals, mixed crystals and modified crystals; the metal powder can be aluminum powder (Al), boron powder (B), magnesium powder (Mg) or alloy powder thereof; the hydrogen storage material can be magnesium hydride (MgH2), aluminum hydride (AlH3), lithium aluminum hydride (LiAlH4), magnesium aluminum hydride (Mg(AlH4)2) and the like, and it is worth noting that the method is also applicable to non-energetic materials; the morphology of the energetic molecular cluster can be spherical, cubic, various cylindrical, various pyramidal and the like, and the energetic molecular cluster of a certain size (the longest side / diameter) can be placed in a larger cubic lattice, which means that the lattice side length is

[0011] Preferably, in the first step, the specific temperature and relative humidity conditions refer to a temperature of 0-100℃ and a relative humidity of 0%-100%.

[0012] Preferably, in the first step, the water molecules with known density under specific temperature and relative humidity conditions are multiplied by n times to make the density of the water molecules ≥0.0001 g / cm 3The modeling meets the modeling requirements of the Materials studio molecular simulation software.

[0013] Preferably, in the second step, when performing the NVT molecular dynamics calculation, the kinetic parameters are set, including: the time is set to 20 ps to 1000 ps, the temperature control method is the Nose method, and the calculation accuracy of structure optimization is greater than or equal to the default Middle accuracy of the Forcite module and needs to consider the displacement factor (Displacement).

[0014] Preferably, in the third step, E is determined according to the formula interaction = E total -E water -E cluster .

[0015] Preferably, in the third step, the calculation accuracy of energy is greater than or equal to the default Middle accuracy of the Forcite module of the Materials studio software.

[0016] Preferably, in the third step, the interaction energy E of the energetic molecular cluster with water molecules under different temperature and relative humidity conditions is calculated interaction , the hygroscopicity of the energetic molecular cluster is evaluated, and the absolute value of E is greater, and the hygroscopicity of the energetic molecular cluster is stronger. interaction

[0017] The evaluation method of the hygroscopicity of the energetic material under different temperature and humidity conditions provided by the present application has the following advantages compared with the prior art method:

[0018] (1) According to the water molecule density under various temperature and humidity conditions, the present application establishes an energetic molecular model and controls the size of the system model, so as to achieve the purpose of evaluating the hygroscopicity of various energetic molecules under any temperature and humidity conditions (temperature: 0-100 DEG C, relative humidity 0%-100%), and is not affected by external environmental factors and human factors.

[0019] (2) The simulation method provided by the present application is simpler, safer and more efficient. The experiment needs a long time from sample preparation to hygroscopicity characterization, while the simulation method can calculate the hygroscopicity of samples under multiple different conditions at the same time, greatly saving the time for evaluating the hygroscopicity of energetic molecules.

[0020] (3) The present application is helpful to speed up the development and application of new energetic materials in the evaluation of the hygroscopicity of energetic materials, and the hygroscopicity results of the energetic materials can be obtained without carrying out experiments, which has very important significance for the selection of energetic materials, and is also suitable for the evaluation of various modified energetic materials. BRIEF DESCRIPTION OF DRAWINGS

[0021] ​Figure 1 It is the unit cell of the ADN crystal in Example 1.

[0022] Figure 2 The radius in Example 1 ADN spherical clusters are placed on sides of length The model in the cubic lattice.

[0023] Figure 3 In Example 1, a material with a density of 0.00409 g / cm³ was filled. 3 The model after water molecules.

[0024] Figure 4 It is the moisture-absorbing model after 100ps of NVT molecular dynamics in Example 1.

[0025] Figure 5 This is the stable ADN moisture absorption model after structural optimization in Example 1.

[0026] Figure 6 These are the molecular energy models of the three systems calculated in Example 1.

[0027] Figure 7 This is a schematic diagram illustrating the principle of the method for evaluating the hygroscopicity of energetic materials under different temperature and humidity conditions as described in this invention. Detailed Implementation

[0028] To further describe the present invention, the following embodiments are provided, but the present invention is not limited to the embodiments described.

[0029] For the modification of many hygroscopic energetic materials, we prefer to evaluate the hygroscopicity of our designed modified materials beforehand, select the optimal scheme from a large number of modification options, and then conduct experiments to verify it. This can significantly reduce experimental costs and time while improving experimental accuracy. Therefore, we propose a theoretical simulation method to study the hygroscopicity of energetic material particles. The advantage of the theoretical method over actual testing is that it can strictly adhere to the required external temperature and humidity, ensuring that the morphology, particle size, and density of the sample model are completely identical for each experiment. This avoids significant errors in experimental data due to differences in environmental conditions and the sample itself.

[0030] Taking ADN as an example, this invention provides a method for evaluating the hygroscopicity of energetic materials under different temperature and humidity conditions, and its schematic diagram is shown in Figure 7.

[0031] Implementation Example 1:

[0032] Step 1: Based on the tables in chemical engineering handbooks or books on chemical principles that contain information on the saturated vapor pressure of water molecules at different temperatures, obtain the density of water molecules at standard atmospheric pressure, 40°C, and 100% saturated humidity. Calculate that the density of water molecules at standard atmospheric pressure, 40°C, and 10% relative humidity is approximately 5.114 × 10⁻⁶. -6 g / cm 3 .

[0033] Step 2: Import the CIF file of ammonium dinitramide (ADN) crystals into Materials Studio 2019 simulation software to perform complete structural optimization of the initial ADN unit cell, making the system architecture more reasonable. Figure 1 The computational precision for structural optimization is set to Ultra-fine (Energy: 2 × 10⁻⁶). -5 kcal / mol, Force: 0.001 kcal / mol / Displacement is set to Then construct a radius of ADN spherical nanoclusters were constructed and the constructed ADN nanoclusters were placed on sides of length The body center position of the cubic lattice ( Figure 2 The water molecule density calculated in the previous step is 5.114 × 10⁻⁶. -6 g / cm 3 Multiply by 200 to get 0.00102 g / cm³ 3 (Because the calculated water molecule density value is too small in actual situations, and the minimum density of molecules added in the Amorphous module of MaterialsStudio 2019 simulation software is 0.0001 g / cm³) 3 Therefore, when adding water molecules, the water molecule density under all temperature and humidity systems should be multiplied by n to ensure that the minimum density of the added water molecules is not less than 0.0001 g / cm³. 3 This achieves the goal of studying the hygroscopic effect of energetic molecules on water molecules under different temperature and humidity conditions, while also meeting the accuracy requirements of simulation software modeling. Water molecules of this density fill the gaps between the ADN clusters and the cubic lattice. Figure 3 ), thus obtaining the initial moisture absorption model of ADN.

[0034] Step 3: Perform NVT molecular dynamics simulation on the constructed AND initial hygroscopic model using the Forcite module of Materials Studio simulation software. Set the molecular dynamics time to 100 ps. Finally, extract the last frame of the model after completing the molecular dynamics calculation. Figure 4The Forcite module is used to perform non-optimized cell structure optimization to eliminate unstable factors such as stress in the structure, resulting in a stable model after moisture absorption. Figure 5 The computational precision for structural optimization is set to Ultra-fine (Energy: 2 × 10⁻⁶). -5 kcal / mol, Force: 0.001 kcal / mol / Displacement is set to

[0035] Step 4: Using the atom selection function, the stable model of the ADN after hygroscopic absorption is split into separate models of individual water molecules and individual energetic molecular clusters. The Forcite module is then used to calculate the system energy of these three models. Figure 6 ), in order: E water = -216.135 kcal / mol, E cluster = -82579.033 kcal / mol, E total = -84334.082 kcal / mol. Finally, by subtracting the energy of the individual energetic molecular cluster and then the energy of the individual water molecule from the energy of the intact system after moisture absorption, the interaction energy of water molecules in this ADN spherical cluster at 40℃ and 10% relative humidity is obtained: E interaction =E total -E water -E cluster = -1538.914 kcal / mol.

[0036] Implementation Example 2:

[0037] Step 1: The density of water molecules under standard atmospheric pressure, 40℃, and 20% relative humidity is calculated to be approximately 1.023 × 10⁻⁶. -5 g / cm 3 .

[0038] Step 2: Import the CIF file of the ADN crystal into Materials Studio 2019 simulation software. Perform full structural optimization on the initial ADN unit cell to make the system architecture more reasonable. Set the calculation accuracy for structural optimization to Ultra-fine (Energy: 2 × 10⁻⁶). -5 kcal / mol, Force: 0.001 kcal / mol / Displacement is set to Then construct a radius of ADN spherical nanoclusters were constructed and the constructed ADN nanoclusters were placed on sides of length The body center of the cubic lattice is located at the position of the water molecule density calculated in the previous step, which is 1.023 × 10⁻⁶. -5 g / cm 3 Multiply by 200 to get 0.00205 g / cm³ 3 (≥0.0001g / cm 3 (Meets software modeling requirements), filling the gaps between ADN clusters and cubic lattice with water molecules of that density.

[0039] Step 3: Perform NVT molecular dynamics simulation on the constructed ADN hygroscopic model using the Forcite module of Materials Studio simulation software. Set the molecular dynamics time to 100 ps. Finally, extract the last frame of the model after completing the molecular dynamics calculation and use the Forcite module to perform non-optimized cell structure optimization to eliminate unstable factors such as stress in the structure, obtaining a stable model after hygroscopic absorption. Set the calculation accuracy of the structure optimization to Ultra-fine (Energy: 2 × 10⁻⁶). -5 kcal / mol, Force: 0.001 kcal / mol / Displacement is set to

[0040] Step 4: Using the atom selection function, the stable model after ADN hygroscopic absorption is split into three models: the model of a single water molecule, the model of a single energetic molecular cluster, and the hygroscopic model of the complete system. The system energies of these three separated models are calculated using the Forcite module, as follows: E water = -695.632 kcal / mol, E cluster = -82416.823 kcal / mol, E total = -85538.839 kcal / mol. Finally, by subtracting the energy of the individual energetic molecular cluster and then the energy of a single water molecule from the energy of the intact system after moisture absorption, the interaction energy of water molecules in this ADN spherical cluster at 40℃ and 20% relative humidity is obtained: E interaction =E total -E water -E cluster = -2426.384 kcal / mol.

[0041] Implementation Example 3:

[0042] Step 1: The density of water molecules under standard atmospheric pressure, 40℃, and 30% relative humidity is calculated to be approximately 1.534 × 10⁻⁶. -5 g / cm 3 .

[0043] Step 2: Import the CIF file of the ADN crystal into Materials Studio 2019 simulation software. Perform full structural optimization on the initial ADN unit cell to make the system architecture more reasonable. Set the calculation accuracy for structural optimization to Ultra-fine (Energy: 2 × 10⁻⁶). -5 kcal / mol, Force: 0.001 kcal / mol / Displacement is set to Then construct a radius of ADN spherical nanoclusters were constructed and the constructed ADN nanoclusters were placed on sides of length The body center of the cubic lattice is located at the position of the water molecule density calculated in the previous step, which is 1.534 × 10⁻⁶. -5 g / cm 3 Multiply by 200 to get 0.00307 g / cm³ 3 (≥0.0001g / cm 3 (Meets software modeling requirements), filling the gaps between ADN clusters and cubic lattice with water molecules of that density.

[0044] Step 3: Perform NVT molecular dynamics simulation on the constructed ADN hygroscopic model using the Forcite module of Materials Studio simulation software. Set the molecular dynamics time to 100 ps. Finally, extract the last frame of the model after completing the molecular dynamics calculation and use the Forcite module to perform non-optimized cell structure optimization to eliminate unstable factors such as stress in the structure, obtaining a stable model after hygroscopic absorption. Set the calculation accuracy of the structure optimization to Ultra-fine (Energy: 2 × 10⁻⁶). -5 kcal / mol, Force: 0.001 kcal / mol / Displacement is set to

[0045] Step 4: Using the atom selection function, the stable model after ADN hygroscopic absorption is split into three models: the model of a single water molecule, the model of a single energetic molecular cluster, and the hygroscopic model of the complete system. The system energies of these three separated models are calculated using the Forcite module, as follows: E water = -1288.881 kcal / mol, E cluster = -82295.940 kcal / mol, E total= -86443.139 kcal / mol. Finally, by subtracting the energy of the individual energetic molecular cluster and then the energy of a single water molecule from the energy of the intact system after moisture absorption, the interaction energy of water molecules in this ADN spherical cluster at 40℃ and 30% relative humidity is obtained: E interaction =E total -E water -E cluster = -2858.318 kcal / mol.

[0046] Implementation Example 4:

[0047] Step 1: The density of water molecules under standard atmospheric pressure, 40℃, and 40% relative humidity is calculated to be approximately 2.046 × 10⁻⁶. -5 g / cm 3 .

[0048] Step 2: Import the CIF file of the ADN crystal into Materials Studio 2019 simulation software. Perform full structural optimization on the initial ADN unit cell to make the system architecture more reasonable. Set the calculation accuracy for structural optimization to Ultra-fine (Energy: 2 × 10⁻⁶). -5 kcal / mol, Force: 0.001 kcal / mol / Displacement is set to Then construct a radius of ADN spherical nanoclusters were constructed and the constructed ADN nanoclusters were placed on sides of length The body center of the cubic lattice is located at the position of the water molecule density calculated in the previous step, which is 2.046 × 10⁻⁶. -5 g / cm 3 Multiply by 200 to get 0.00409 g / cm³ 3 (≥0.0001g / cm 3 (Meets software modeling requirements), filling the gaps between ADN clusters and cubic lattice with water molecules of that density.

[0049] Step 3: Perform NVT molecular dynamics simulation on the constructed ADN hygroscopic model using the Forcite module of Materials Studio simulation software. Set the molecular dynamics time to 100 ps. Finally, extract the last frame of the model after completing the molecular dynamics calculation and use the Forcite module to perform non-optimized cell structure optimization to eliminate unstable factors such as stress in the structure, obtaining a stable model after hygroscopic absorption. Set the calculation accuracy of the structure optimization to Ultra-fine (Energy: 2 × 10⁻⁶). -5 kcal / mol, Force: 0.001 kcal / mol / Displacement is set to

[0050] Step 4: Using the atom selection function, the stable model after ADN hygroscopic absorption is split into three models: the model of a single water molecule, the model of a single energetic molecular cluster, and the hygroscopic model of the complete system. The system energies of these three separated models are calculated using the Forcite module, as follows: E water = -1906.746 kcal / mol, E cluster = -81905.513 kcal / mol, E total = -87476.106 kcal / mol. Finally, by subtracting the energy of the individual energetic molecular cluster and then the energy of a single water molecule from the energy of the intact system after moisture absorption, the interaction energy of water molecules in this ADN spherical cluster at 40℃ and 40% relative humidity is obtained as: E interaction =E total -E water -E cluster = -3663.847 kcal / mol.

[0051] Implementation Example 5:

[0052] Step 1: The density of water molecules under standard atmospheric pressure, 40℃, and 50% relative humidity is calculated to be approximately 2.557 × 10⁻⁶. -5 g / cm 3 .

[0053] Step 2: Import the CIF file of the ADN crystal into Materials Studio 2019 simulation software. Perform full structural optimization on the initial ADN unit cell to make the system architecture more reasonable. Set the calculation accuracy for structural optimization to Ultra-fine (Energy: 2 × 10⁻⁶). -5 kcal / mol, Force: 0.001 kcal / mol / Displacement is set to Then construct a radius of ADN spherical nanoclusters were constructed and the constructed ADN nanoclusters were placed on sides of length The body center of the cubic lattice is located at the position of the water molecule density calculated in the previous step, which is 2.557 × 10⁻⁶. -5 g / cm 3 Multiply by 200 to get 0.00511 g / cm³ 3 (≥0.0001g / cm 3 (Meets software modeling requirements), filling the gaps between ADN clusters and cubic lattice with water molecules of that density.

[0054] Step 3: Perform NVT molecular dynamics simulation on the constructed ADN hygroscopic model using the Forcite module of Materials Studio simulation software. Set the molecular dynamics time to 100 ps. Finally, extract the last frame of the model after completing the molecular dynamics calculation and use the Forcite module to perform non-optimized cell structure optimization to eliminate unstable factors such as stress in the structure, obtaining a stable model after hygroscopic absorption. Set the calculation accuracy of the structure optimization to Ultra-fine (Energy: 2 × 10⁻⁶). -5 kcal / mol, Force: 0.001 kcal / mol / Displacement is set to

[0055] Step 4: Using the atom selection function, the stable model after ADN hygroscopic absorption is split into three models: the model of a single water molecule, the model of a single energetic molecular cluster, and the hygroscopic model of the complete system. The system energies of these three separated models are calculated using the Forcite module, as follows: E water = -2701.862 kcal / mol, E cluster = -81576.847 kcal / mol, E total = -88930.299 kcal / mol. Finally, by subtracting the energy of the individual energetic molecular cluster and then the energy of a single water molecule from the energy of the intact system after moisture absorption, the interaction energy of water molecules in this ADN spherical cluster at 40℃ and 50% relative humidity is obtained as: E interaction =E total -E water -E cluster = -4651.590 kcal / mol.

[0056] Implementation Example 6:

[0057] Step 1: The density of water molecules under standard atmospheric pressure, 40℃, and 60% relative humidity is calculated to be approximately 3.068 × 10⁻⁶. -5 g / cm 3 .

[0058] Step 2: Import the CIF file of the ADN crystal into Materials Studio 2019 simulation software. Perform full structural optimization on the initial ADN unit cell to make the system architecture more reasonable. Set the calculation accuracy for structural optimization to Ultra-fine (Energy: 2 × 10⁻⁶). -5 kcal / mol, Force: 0.001 kcal / mol / Displacement is set to Then construct a radius of ADN spherical nanoclusters were constructed and the constructed ADN nanoclusters were placed on sides of length The body center of the cubic lattice is located, and the water molecule density calculated in the previous step is 3.068 × 10⁻⁶. -5 g / cm 3 Multiply by 200 to get 0.00614 g / cm³ 3 (≥0.0001g / cm 3 (Meets software modeling requirements), filling the gaps between ADN clusters and cubic lattice with water molecules of that density.

[0059] Step 3: Perform NVT molecular dynamics simulation on the constructed ADN hygroscopic model using the Forcite module of Materials Studio simulation software. Set the molecular dynamics time to 100 ps. Finally, extract the last frame of the model after completing the molecular dynamics calculation and use the Forcite module to perform non-optimized cell structure optimization to eliminate unstable factors such as stress in the structure, obtaining a stable model after hygroscopic absorption. Set the calculation accuracy of the structure optimization to Ultra-fine (Energy: 2 × 10⁻⁶). -5 kcal / mol, Force: 0.001 kcal / mol / Displacement is set to

[0060] Step 4: Using the atom selection function, the stable model after ADN hygroscopic absorption is split into three models: the model of a single water molecule, the model of a single energetic molecular cluster, and the hygroscopic model of the complete system. The system energies of these three separated models are calculated using the Forcite module, as follows: E water = -3568.760 kcal / mol, E cluster = -81556.012 kcal / mol, E total = -89888.618 kcal / mol. Finally, by subtracting the energy of the individual energetic molecular cluster and then the energy of a single water molecule from the energy of the intact system after moisture absorption, the interaction energy of water molecules in this ADN spherical cluster at 40℃ and 60% relative humidity is obtained as: E interaction =E total -E water -E cluster = -4763.846 kcal / mol.

[0061] Implementation Example 7:

[0062] Step 1: The density of water molecules under standard atmospheric pressure, 40℃, and 70% relative humidity is calculated to be approximately 3.580 × 10⁻⁶. -5 g / cm 3 .

[0063] Step 2: Import the CIF file of the ADN crystal into Materials Studio 2019 simulation software. Perform full structural optimization on the initial ADN unit cell to make the system architecture more reasonable. Set the calculation accuracy for structural optimization to Ultra-fine (Energy: 2 × 10⁻⁶). -5 kcal / mol, Force: 0.001 kcal / mol / Displacement is set to Then construct a radius of ADN spherical nanoclusters were constructed and the constructed ADN nanoclusters were placed on sides of length The body center position of the cubic lattice, with the water molecule density calculated in the previous step as 3.580 × 10⁻⁶. -5 g / cm 3 Multiply by 200 to get 0.00716 g / cm³ 3 (≥0.0001g / cm 3 (Meets software modeling requirements), filling the gaps between ADN clusters and cubic lattice with water molecules of that density.

[0064] Step 3: Perform NVT molecular dynamics simulation on the constructed ADN hygroscopic model using the Forcite module of Materials Studio simulation software. Set the molecular dynamics time to 100 ps. Finally, extract the last frame of the model after completing the molecular dynamics calculation and use the Forcite module to perform non-optimized cell structure optimization to eliminate unstable factors such as stress in the structure, obtaining a stable model after hygroscopic absorption. Set the calculation accuracy of the structure optimization to Ultra-fine (Energy: 2 × 10⁻⁶). -5 kcal / mol, Force: 0.001 kcal / mol / Displacement is set to

[0065] Step 4: Using the atom selection function, the stable model after ADN hygroscopic absorption is split into three models: the model of a single water molecule, the model of a single energetic molecular cluster, and the hygroscopic model of the complete system. The system energies of these three separated models are calculated using the Forcite module, as follows: E water = -4267.819 kcal / mol, E cluster= -81167.758 kcal / mol, E total = -90816.034 kcal / mol. Finally, by subtracting the energy of the individual energetic molecular cluster and then the energy of a single water molecule from the energy of the intact system after moisture absorption, the interaction energy of water molecules in this ADN spherical cluster at 40℃ and 70% relative humidity is obtained: E interaction =E total -E water -E cluster = -5380.457 kcal / mol.

[0066] Implementation Example 8:

[0067] Step 1: The density of water molecules under standard atmospheric pressure, 40℃, and 80% relative humidity is calculated to be approximately 4.091 × 10⁻⁶. -5 g / cm 3 .

[0068] Step 2: Import the CIF file of the ADN crystal into Materials Studio 2019 simulation software. Perform full structural optimization on the initial ADN unit cell to make the system architecture more reasonable. Set the calculation accuracy for structural optimization to Ultra-fine (Energy: 2 × 10⁻⁶). -5 kcal / mol, Force: 0.001 kcal / mol / Displacement is set to Then construct a radius of ADN spherical nanoclusters were constructed and the constructed ADN nanoclusters were placed on sides of length The body center of the cubic lattice is located at the position of the water molecule density calculated in the previous step, which is 4.091 × 10⁻⁶. -5 g / cm 3 Multiply by 200 to get 0.00818 g / cm³ 3 (≥0.0001g / cm 3 (Meets software modeling requirements), filling the gaps between ADN clusters and cubic lattice with water molecules of that density.

[0069] Step 3: Perform NVT molecular dynamics simulation on the constructed ADN hygroscopic model using the Forcite module of Materials Studio simulation software. Set the molecular dynamics time to 100 ps. Finally, extract the last frame of the model after completing the molecular dynamics calculation and use the Forcite module to perform non-optimized cell structure optimization to eliminate unstable factors such as stress in the structure, obtaining a stable model after hygroscopic absorption. Set the calculation accuracy of the structure optimization to Ultra-fine (Energy: 2 × 10⁻⁶).-5 kcal / mol, Force: 0.001 kcal / mol / Displacement is set to

[0070] Step 4: Using the atom selection function, the stable model after ADN hygroscopic absorption is split into three models: the model of a single water molecule, the model of a single energetic molecular cluster, and the hygroscopic model of the complete system. The system energies of these three separated models are calculated using the Forcite module, as follows: E water = -5445.833 kcal / mol, E cluster = -81311.527 kcal / mol, E total = -92178.651 kcal / mol. Finally, by subtracting the energy of the individual energetic molecular clusters from the energy of the intact system after moisture absorption, and then subtracting the energy of a single water molecule, we obtain the water molecule interaction energy of this ADN spherical cluster at 40℃ and 80% relative humidity: E interaction =E total -E water -E cluster = -5421.291 kcal / mol.

[0071] Implementation Example 9:

[0072] Step 1: The density of water molecules under standard atmospheric pressure, 40℃, and 90% relative humidity is calculated to be approximately 4.603 × 10⁻⁶. -5 g / cm 3 .

[0073] Step 2: Import the CIF file of the ADN crystal into Materials Studio 2019 simulation software. Perform full structural optimization on the initial ADN unit cell to make the system architecture more reasonable. Set the calculation accuracy for structural optimization to Ultra-fine (Energy: 2 × 10⁻⁶). -5 kcal / mol, Force: 0.001 kcal / mol / Displacement is set to Then construct a radius of ADN spherical nanoclusters were constructed and the constructed ADN nanoclusters were placed on sides of length The body center position of the cubic lattice is given by the water molecule density calculated in the previous step, which is 4.603 × 10⁻⁶. -5 g / cm 3 Multiply by 200 to get 0.00921 g / cm³ 3 (≥0.0001g / cm 3(Meets software modeling requirements), filling the gaps between ADN clusters and cubic lattice with water molecules of that density.

[0074] Step 3: Perform NVT molecular dynamics simulation on the constructed ADN hygroscopic model using the Forcite module of Materials Studio simulation software. Set the molecular dynamics time to 100 ps. Finally, extract the last frame of the model after completing the molecular dynamics calculation and use the Forcite module to perform non-optimized cell structure optimization to eliminate unstable factors such as stress in the structure, obtaining a stable model after hygroscopic absorption. Set the calculation accuracy of the structure optimization to Ultra-fine (Energy: 2 × 10⁻⁶). -5 kcal / mol, Force: 0.001 kcal / mol / Displacement is set to

[0075] Step 4: Using the atom selection function, the stable model after ADN hygroscopic absorption is split into three models: the model of a single water molecule, the model of a single energetic molecular cluster, and the hygroscopic model of the complete system. The system energies of these three separated models are calculated using the Forcite module, as follows: E water = -6279.108 kcal / mol, E cluster = -81009.285 kcal / mol, E total = -93275.496 kcal / mol. Finally, by subtracting the energy of the individual energetic molecular cluster and then the energy of a single water molecule from the energy of the intact system after moisture absorption, the interaction energy of water molecules in this ADN spherical cluster at 40℃ and 90% relative humidity is obtained as: E interaction =E total -E water -E cluster = -5987.103 kcal / mol.

[0076] Implementation Example 10:

[0077] Step 1: The density of water molecules under standard atmospheric pressure, 40℃, and 100% relative humidity is calculated to be approximately 5.114 × 10⁻⁶. -5 g / cm 3 .

[0078] Step 2: Import the CIF file of the ADN crystal into Materials Studio 2019 simulation software. Perform full structural optimization on the initial ADN unit cell to make the system architecture more reasonable. Set the calculation accuracy for structural optimization to Ultra-fine (Energy: 2 × 10⁻⁶).-5 kcal / mol, Force: 0.001 kcal / mol / Displacement is set to Then construct a radius of ADN spherical nanoclusters were constructed and the constructed ADN nanoclusters were placed on sides of length The body center of the cubic lattice is located, and the water molecule density calculated in the previous step is 5.114 × 10⁻⁶. -5 g / cm 3 Multiply by 200 to get 0.01023 g / cm³ 3 (≥0.0001g / cm 3 (Meets software modeling requirements), filling the gaps between ADN clusters and cubic lattice with water molecules of that density.

[0079] Step 3: Perform NVT molecular dynamics simulation on the constructed ADN hygroscopic model using the Forcite module of Materials Studio simulation software. Set the molecular dynamics time to 100 ps. Finally, extract the last frame of the model after completing the molecular dynamics calculation and use the Forcite module to perform non-optimized cell structure optimization to eliminate unstable factors such as stress in the structure, obtaining a stable model after hygroscopic absorption. Set the calculation accuracy of the structure optimization to Ultra-fine (Energy: 2 × 10⁻⁶). -5 kcal / mol, Force: 0.001 kcal / mol / Displacement is set to

[0080] Step 4: Using the atom selection function, the stable model after ADN hygroscopic absorption is split into three models: the model of a single water molecule, the model of a single energetic molecular cluster, and the hygroscopic model of the complete system. The system energies of these three separated models are calculated using the Forcite module, as follows: E water = -7159.297 kcal / mol, E cluster = -80812.573 kcal / mol, E total = -94517.628 kcal / mol. Finally, by subtracting the energy of the individual energetic molecular cluster and then the energy of a single water molecule from the energy of the intact system after moisture absorption, the interaction energy of water molecules in this ADN spherical cluster at 40℃ and 100% relative humidity is obtained as: E interaction =E total -E water -E cluster = -6545.758 kcal / mol.

[0081] Implementation Example 11:

[0082] Step 1: The density of water molecules under standard atmospheric pressure, 0℃, and 40% relative humidity is calculated to be approximately 1.936 × 10⁻⁶. -6 g / cm 3 .

[0083] Step 2: Import the CIF file of the ADN crystal into Materials Studio 2019 simulation software. Perform full structural optimization on the initial ADN unit cell to make the system architecture more reasonable. Set the calculation accuracy for structural optimization to Ultra-fine (Energy: 2 × 10⁻⁶). -5 kcal / mol, Force: 0.001 kcal / mol / Displacement is set to Then construct a radius of ADN spherical nanoclusters were constructed and the constructed ADN nanoclusters were placed on sides of length The body center of the cubic lattice is located at the position of the water molecule density calculated in the previous step, which is 1.936 × 10⁻⁶. -6 g / cm 3 Multiply by 200 to get 0.00039 g / cm³ 3 (≥0.0001g / cm 3 (Meets software modeling requirements), filling the gaps between ADN clusters and cubic lattice with water molecules of that density.

[0084] Step 3: Perform NVT molecular dynamics simulation on the constructed ADN hygroscopic model using the Forcite module of Materials Studio simulation software. Set the molecular dynamics time to 100 ps. Finally, extract the last frame of the model after completing the molecular dynamics calculation and use the Forcite module to perform non-optimized cell structure optimization to eliminate unstable factors such as stress in the structure, obtaining a stable model after hygroscopic absorption. Set the calculation accuracy of the structure optimization to Ultra-fine (Energy: 2 × 10⁻⁶). -5 kcal / mol, Force: 0.001 kcal / mol / Displacement is set to

[0085] Step 4: Using the atom selection function, the stable model after ADN hygroscopic absorption is split into three models: the model of a single water molecule, the model of a single energetic molecular cluster, and the hygroscopic model of the complete system. The system energies of these three separated models are calculated using the Forcite module, as follows: E water= -58.448 kcal / mol, E cluster = -82935.859 kcal / mol, E total = -83683.110 kcal / mol. Finally, by subtracting the energy of the individual energetic molecular clusters from the energy of the intact system after moisture absorption, and then subtracting the energy of a single water molecule, we obtain the water molecule interaction energy of this ADN spherical cluster at 0℃ and 40% relative humidity: E interaction =E total -E water -E cluster = -688.803 kcal / mol.

[0086] Implementation Example 12:

[0087] Step 1: The density of water molecules under standard atmospheric pressure, 20℃, and 40% relative humidity is calculated to be approximately 6.876 × 10⁻⁶. -6 g / cm 3 .

[0088] Step 2: Import the CIF file of the ADN crystal into Materials Studio 2019 simulation software. Perform full structural optimization on the initial ADN unit cell to make the system architecture more reasonable. Set the calculation accuracy for structural optimization to Ultra-fine (Energy: 2 × 10⁻⁶). -5 kcal / mol, Force: 0.001 kcal / mol / Displacement is set to Then construct a radius of ADN spherical nanoclusters were constructed and the constructed ADN nanoclusters were placed on sides of length The body center position of the cubic lattice is given by the water molecule density calculated in the previous step as 6.876 × 10⁻⁶. -6 g / cm 3 Multiply by 200 to get 0.00138 g / cm³ 3 (≥0.0001g / cm 3 (Meets software modeling requirements), filling the gaps between ADN clusters and cubic lattice with water molecules of that density.

[0089] Step 3: Perform NVT molecular dynamics simulation on the constructed ADN hygroscopic model using the Forcite module of Materials Studio simulation software. Set the molecular dynamics time to 100 ps. Finally, extract the last frame of the model after completing the molecular dynamics calculation and use the Forcite module to perform non-optimized cell structure optimization to eliminate unstable factors such as stress in the structure, obtaining a stable model after hygroscopic absorption. Set the calculation accuracy of the structure optimization to Ultra-fine (Energy: 2 × 10⁻⁶). -5 kcal / mol, Force: 0.001 kcal / mol / Displacement is set to

[0090] Step 4: Using the atom selection function, the stable model after ADN hygroscopic absorption is split into three models: the model of a single water molecule, the model of a single energetic molecular cluster, and the hygroscopic model of the complete system. The system energies of these three separated models are calculated using the Forcite module, as follows: E water = -437.215 kcal / mol, E cluster = -82665.744 kcal / mol, E total = -84726.504 kcal / mol. Finally, by subtracting the energy of the individual energetic molecular cluster and then the energy of a single water molecule from the energy of the intact system after moisture absorption, the interaction energy of water molecules in this ADN spherical cluster at 20℃ and 40% relative humidity is obtained: E interaction =E total -E water -E cluster = -1623.545 kcal / mol.

[0091] Implementation Example 13:

[0092] Step 1: The density of water molecules under standard atmospheric pressure, 60℃, and 40% relative humidity is calculated to be approximately 5.204 × 10⁻⁶. -5 g / cm 3 .

[0093] Step 2: Import the CIF file of the ADN crystal into Materials Studio 2019 simulation software. Perform full structural optimization on the initial ADN unit cell to make the system architecture more reasonable. Set the calculation accuracy for structural optimization to Ultra-fine (Energy: 2 × 10⁻⁶). -5 kcal / mol, Force: 0.001 kcal / mol / Displacement is set to Then construct a radius of ADN spherical nanoclusters were constructed and the constructed ADN nanoclusters were placed on sides of length The body center of the cubic lattice is located at the position of the water molecule density calculated in the previous step, which is 5.204 × 10⁻⁶. -5 g / cm 3 Multiply by 200 to get 0.01041 g / cm³ 3 (≥0.0001g / cm 3 (Meets software modeling requirements), filling the gaps between ADN clusters and cubic lattice with water molecules of that density.

[0094] Step 3: Perform NVT molecular dynamics simulation on the constructed ADN hygroscopic model using the Forcite module of Materials Studio simulation software. Set the molecular dynamics time to 100 ps. Finally, extract the last frame of the model after completing the molecular dynamics calculation and use the Forcite module to perform non-optimized cell structure optimization to eliminate unstable factors such as stress in the structure, obtaining a stable model after hygroscopic absorption. Set the calculation accuracy of the structure optimization to Ultra-fine (Energy: 2 × 10⁻⁶). -5 kcal / mol, Force: 0.001 kcal / mol / Displacement is set to

[0095] Step 4: Using the atom selection function, the stable model after ADN hygroscopic absorption is split into three models: the model of a single water molecule, the model of a single energetic molecular cluster, and the hygroscopic model of the complete system. The system energies of these three separated models are calculated using the Forcite module, as follows: E water = -6939.613 kcal / mol, E cluster = -80771.684 kcal / mol, E total = -94104.408 kcal / mol. Finally, by subtracting the energy of the individual energetic molecular cluster and then the energy of a single water molecule from the energy of the intact system after moisture absorption, the interaction energy of water molecules in this ADN spherical cluster at 60℃ and 40% relative humidity is obtained as: E interaction =E total -E water -E cluster = -6393.111 kcal / mol.

[0096] Implementation Example 14:

[0097] Step 1: The density of water molecules under standard atmospheric pressure, 40℃, and 80% relative humidity is calculated to be approximately 4.091 × 10⁻⁶. -5 g / cm 3 .

[0098] Step 2: Import the CIF file of ammonium nitrate (AN) crystals into Materials Studio 2019 simulation software. Perform full structural optimization on the initial AN unit cell to make the system architecture more reasonable. Set the calculation accuracy for structural optimization to Ultra-fine (Energy: 2 × 10⁻⁶). -5 kcal / mol, Force: 0.001 kcal / mol / Displacement is set to Then construct a radius of AN spherical nanoclusters were constructed and the constructed AN nanoclusters were placed on sides of length The body center of the cubic lattice is located at the position of the water molecule density calculated in the previous step, which is 4.091 × 10⁻⁶. -5 g / cm 3 Multiply by 200 to get 0.00818 g / cm³ 3 (≥0.0001g / cm 3 (Meets software modeling requirements), filling the gaps between AN clusters and cubic lattice with water molecules of that density.

[0099] Step 3: Perform NVT molecular dynamics simulation on the constructed AN hygroscopic model using the Forcite module of Materials Studio simulation software. Set the molecular dynamics time to 100 ps. Finally, extract the last frame of the model after completing the molecular dynamics calculation and use the Forcite module to perform non-optimized unit cell structure optimization to eliminate unstable factors such as stress in the structure, obtaining a stable model after hygroscopic absorption. Set the calculation accuracy of the structure optimization to Ultra-fine (Energy: 2 × 10⁻⁶). -5 kcal / mol, Force: 0.001 kcal / mol / Displacement is set to

[0100] Step 4: Using the atom selection function, the stable model of AN after hygroscopic absorption is split into three models: the model of a single water molecule, the model of a single energetic molecular cluster, and the hygroscopic model of the complete system. The system energies of these three separated models are calculated using the Forcite module, as follows: E water = -2226.375 kcal / mol, E cluster= -73165.193 kcal / mol, E total = -80708.985 kcal / mol. Finally, by subtracting the energy of the individual energetic molecular cluster and the energy of a single water molecule from the energy of the intact system after moisture absorption, the interaction energy of water molecules in the AN spherical cluster at 40℃ and 80% relative humidity is obtained as: E interaction =E total -E water -E cluster = -5317.417 kcal / mol.

[0101] Implementation Example 15:

[0102] Step 1: The density of water molecules under standard atmospheric pressure, 40℃, and 90% relative humidity is calculated to be approximately 4.603 × 10⁻⁶. -5 g / cm 3 .

[0103] Step 2: Import the CIF file of the AN crystal into Materials Studio 2019 simulation software. Perform full structural optimization on the initial unit cell of AN to make the system architecture more reasonable. Set the calculation accuracy of the structural optimization to Ultra-fine (Energy: 2 × 10⁻⁶). -5 kcal / mol, Force: 0.001 kcal / mol / Displacement is set to Then construct a radius of AN spherical nanoclusters were constructed and the constructed AN nanoclusters were placed on sides of length The body center position of the cubic lattice is given by the water molecule density calculated in the previous step, which is 4.603 × 10⁻⁶. -5 g / cm 3 Multiply by 200 to get 0.00921 g / cm³ 3 (≥0.0001g / cm 3 (Meets software modeling requirements), filling the gaps between AN clusters and cubic lattice with water molecules of that density.

[0104] Step 3: Perform NVT molecular dynamics simulation on the constructed AN hygroscopic model using the Forcite module of Materials Studio simulation software. Set the molecular dynamics time to 100 ps. Finally, extract the last frame of the model after completing the molecular dynamics calculation and use the Forcite module to perform non-optimized unit cell structure optimization to eliminate unstable factors such as stress in the structure, obtaining a stable model after hygroscopic absorption. Set the calculation accuracy of the structure optimization to Ultra-fine (Energy: 2 × 10⁻⁶). -5kcal / mol, Force: 0.001 kcal / mol / Displacement is set to

[0105] Step 4: Using the atom selection function, the stable model of AN after hygroscopic absorption is split into three models: the model of a single water molecule, the model of a single energetic molecular cluster, and the hygroscopic model of the complete system. The system energies of these three separated models are calculated using the Forcite module, as follows: E water = -3156.338 kcal / mol, E cluster = -73138.980 kcal / mol, E total = -81965.632 kcal / mol. Finally, by subtracting the energy of the individual energetic molecular cluster and then the energy of a single water molecule from the energy of the intact system after moisture absorption, the interaction energy of water molecules in the AN spherical cluster at 40℃ and 90% relative humidity is obtained as: E interaction =E total -E water -E cluster = -5670.314 kcal / mol.

[0106] Data Analysis:

[0107] As shown in Examples 1-10, when the relative humidity of ADN increases from 10% to 100% at 40°C, its hygroscopic capacity gradually increases (Table 1), and the simulation results are consistent with the actual results.

[0108] Table 1. Interaction energies (40°C) between ADN and water molecules in Examples 1-10

[0109]

[0110] As shown in Examples 4, 11, 12, and 13, the hygroscopic capacity of ADN gradually increases as the ambient temperature increases from 0°C to 60°C under 40% relative humidity conditions (Table 2), and the simulation results are consistent with the actual results.

[0111] Table 2. Interaction energies between ADN and water molecules in Examples 4, 11, 12, and 13 (40% RH)

[0112]

[0113] As shown in Examples 8, 9, 14, and 15, when both ADN and AN are at 40°C, their hygroscopic capacity gradually increases with increasing ambient temperature. Moreover, under the same conditions, ADN absorbs moisture more easily than AN (Table 3), and the simulation results are consistent with the actual results.

[0114] Table 3 shows the interaction energies (40°C) between ADN and AN with water molecules in Examples 8, 9, 14, and 15.

[0115]

[0116]

[0117] The method and results of this invention will play a significant role in evaluating the hygroscopicity of energetic materials and predicting the modification effect of hygroscopic energetic materials. It is also suitable for evaluating the hygroscopicity of non-energetic materials.

Claims

1. A method for evaluating the hygroscopicity of energetic materials under different temperature and humidity conditions, characterized in that, Specifically, the following steps are included: The first step is to import the standard CIF file of the initial unit cell of the energetic molecule into the Materials Studio molecular simulation software, construct an energetic molecular cluster of a certain size, and place the constructed energetic molecular cluster in a larger cubic lattice. Then, multiply the density of water molecules known under specific temperature and relative humidity conditions by n and fill the space between the energetic molecular cluster and the cubic lattice to construct the initial model. The second step is to perform NVT molecular dynamics calculations on the constructed initial model. After the molecular dynamics calculations are completed, the last frame of the model is extracted and the Forcite module is used to perform non-optimized unit cell structure optimization to eliminate structural instability factors in the structure, and obtain the stable model M after moisture absorption. The third step involves decomposing the stable model M after moisture absorption, extracting model M1 (individual water molecules) and model M2 (individual energetic molecular clusters), and using the Forcite module to calculate the system energy of these three models, i.e., the energy E of M1. water Energy E of M2 cluster Energy E of M total Finally, the interaction energy E between this energetic molecular cluster and water molecules under specific temperature and relative humidity conditions was obtained. interaction The hygroscopicity of the energetic molecular cluster was evaluated by measuring the interaction energy between the energetic molecular cluster and water molecules under different temperature and relative humidity conditions. Among them, an energetic molecular cluster of a certain size refers to 10 Å ~ 100 Å, and placed in a larger cubic lattice refers to a lattice with a side length of 100 Å ~ 500 Å; In the first step, the specific temperature and relative humidity conditions refer to a temperature of 0 ~ 100 ℃ and a relative humidity of 0% ~ 100%.

2. The evaluation method as described in claim 1, characterized in that, In the first step, the density of water molecules known under specific temperature and relative humidity conditions is multiplied by n to ensure that the density of the water molecules is ≥ 0.0001 g / cm³. 3 It meets the modeling requirements of Materialsstudio molecular simulation software.

3. The evaluation method as described in claim 1, characterized in that, In the second step, when performing NVT molecular dynamics calculations, the dynamic parameters are set as follows: the time is set to 20ps ~ 1000ps, the temperature control method is the Nose method, and the calculation accuracy of the structure optimization is greater than or equal to the default Middle accuracy of the Forcite module and the displacement factor needs to be considered.

4. The evaluation method as described in claim 1, characterized in that, In the third step, E is determined according to the following formula. interaction : AND interaction = And total - AND water - AND cluster 。 5. The evaluation method as described in claim 1, characterized in that, In the third step, the energy calculation accuracy of each model is greater than or equal to the default Middle accuracy of the Forcite module in Materials Studio software.

6. The evaluation method as described in claim 1, characterized in that, In the third step, the interaction energy E between energetic molecular clusters and water molecules under different temperature and relative humidity conditions is used. interaction The hygroscopicity of this energetic molecular cluster was evaluated. interaction The larger the absolute value, the stronger the hygroscopic ability of the energetic molecular cluster.

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