A method for simulating initial stages of hydrolysis of teos based on reaxff molecular dynamics

Abstract

This invention relates to the fields of sol-gel process simulation and molecular dynamics, specifically a method for simulating the initial stage of TEOS hydrolysis based on ReaxFF molecular dynamics. It aims to address the problem that existing experimental techniques are insufficient to capture and analyze the dynamic processes of the initial stage of TEOS hydrolysis at the atomic scale. The method includes: constructing an initial amorphous model containing TEOS, ethanol, water, and citric acid using Packmol software, wherein the molecular ratio of TEOS, ethanol, and water is 1:(4~6):(6~8), and the initial density of the system is 200~250 kg / m³. 3 The model was structurally optimized and relaxed; ReaxFF force fields were used to perform molecular dynamics simulations of the reaction under at least two temperature conditions in the range of 298K to 700K; the bonding information, species information and thermodynamic quantities in the trajectory file were output and analyzed, covering reactant consumption, evolution of key chemical bonds and evolution of hydrolysis intermediates; the influence of temperature on the initial stage of hydrolysis and the range of optimal reaction conditions were determined based on the analysis results.

Description

Technical Field

[0001] This invention relates to the fields of sol-gel process simulation and molecular dynamics, specifically to a method for simulating the initial stage of TEOS hydrolysis based on ReaxFF molecular dynamics. Background Technology

[0002] Tetraethyl orthosilicate (TEOS) is one of the most commonly used precursors for preparing silica aerogels. Its hydrolysis and condensation reactions jointly determine the evolution path of the gel network, thus affecting the microstructure and macroscopic properties of the aerogel. In the sol-gel process, the hydrolysis of TEOS is a key initial step that determines the rate of subsequent condensation reactions, gelation time, and the structure of the final product. A deep understanding of the initial stage mechanism of TEOS hydrolysis, especially the influence of temperature on the hydrolysis reaction, has important theoretical guiding significance for optimizing aerogel preparation processes and achieving targeted control of material properties.

[0003] However, limited by the spatiotemporal resolution of experimental methods, direct atomic-scale evidence for the initial steps of the TEOS hydrolysis reaction remains lacking at the molecular level. While conventional experimental methods such as nuclear magnetic resonance (NMR) and Fourier transform infrared spectroscopy (FTIR) can monitor functional group changes, they struggle to track the dynamics of chemical bond breaking and formation during hydrolysis in real time, and cannot capture the evolution of short-lived intermediates. Although the mechanism of temperature, a key factor influencing the hydrolysis rate, has been qualitatively understood at the macroscopic experimental level, how temperature regulates the kinetics of each step of the hydrolysis reaction and affects the distribution and evolution of hydrolysis intermediates at the molecular scale still lacks systematic theoretical explanation. This restricts the precise optimization of aerogel preparation processes, especially when the degree of hydrolysis needs to be controlled to achieve a specific gel structure, lacking reliable molecular-level guidance.

[0004] Reaction molecular dynamics (ReaxFF) MD simulation, as an advanced theoretical research method, can track bond formation and breaking behavior in chemical reactions in real time, revealing reaction mechanisms at the atomic scale and providing a powerful tool for studying the initial stages of TEOS hydrolysis. Based on bond-level dependent force field parameters, this method can simulate complex chemical reaction systems without pre-setting reaction pathways and has been successfully applied to the mechanism study of pyrolysis, oxidation, and hydrolysis reactions of silicate materials. Numerous simulation studies have demonstrated that molecular dynamics simulations can be used to conduct in-depth and systematic studies of chemical reaction mechanisms, with results showing good agreement with experimental phenomena, effectively guiding the synthesis and application of materials.

[0005] Currently, although there are reports in the literature on the use of molecular dynamics to study silicate systems, detailed case studies using the ReaxFF method to systematically investigate the molecular mechanism, intermediate evolution, and stepwise hydrolysis characteristics of the initial stage of TEOS hydrolysis are still lacking. Temperature affects the effective collision frequency and the probability of crossing the reaction energy barrier by changing the kinetic energy of reactant molecules, thereby regulating the rate and pathway of the hydrolysis reaction; the microscopic details of this process have not yet been fully revealed.

[0006] Therefore, it is urgent to establish a simulation method for the initial stage of TEOS hydrolysis based on ReaxFF molecular dynamics, to reveal the influence of temperature on the dynamic process of TEOS step-by-step hydrolysis and the evolution law of intermediates at the molecular level, to provide a theoretical basis for the optimization of the sol-gel process of silica aerogels, and to help the controllable preparation of high-performance aerogel materials. Summary of the Invention

[0007] The purpose of this invention is to address the problem that existing experimental techniques are insufficient to capture and analyze the dynamic process of the initial stage of TEOS (tetraethyl orthosilicate) hydrolysis at the atomic scale. By providing a simulation method based on ReaxFF molecular dynamics, this invention reveals the influence of temperature on the stepwise hydrolysis mechanism and intermediate evolution of TEOS at the molecular level, thereby providing theoretical support for the optimization of the sol-gel process of silica aerogels.

[0008] To achieve the above objectives, the present invention adopts the following technical solution:

[0009] This invention provides a method for simulating the initial stage of TEOS hydrolysis based on ReaxFF molecular dynamics, the specific steps of which are as follows:

[0010] Step 1: Using Packmol software, construct an initial amorphous model containing TEOS, ethanol, water, and citric acid molecules, where the molecular ratio of tetraethyl orthosilicate (TEOS), ethanol, and water is 1:(4~6):(6~8), and the initial density of the system is 200~250 kg / m³. 3 ;

[0011] Step 2: Optimize and relax the structure of the constructed initial model to obtain a stable initial configuration with reasonable energy.

[0012] Step 3: Using the ReaxFF force field, perform reaction molecular dynamics simulations on the equilibrium model under at least two different temperature conditions in the range of 298 K to 700 K;

[0013] Step 4: Output and analyze the trajectory files, bonding information, species information and thermodynamic quantities in the reaction simulation process, including reactant consumption analysis, key chemical bond evolution analysis and hydrolysis intermediate evolution analysis.

[0014] Step 5: Based on the simulation results, analyze the influence of temperature on the initial stage of TEOS hydrolysis and determine the optimal range of hydrolysis reaction conditions.

[0015] In the above scheme, in step 1, the initial molecular ratio is set as n(TEOS):n(EtOH):n(H2O)=1:5:7, where EtOH represents ethanol, and the initial density is set as 230 kg / m³.

[0016] In the above scheme, in step 2, the conjugate gradient algorithm is used to minimize the energy of the model so that the system reaches an equilibrium state.

[0017] In the above scheme, in step 3, the simulation uses the large-scale molecular parallel simulator LAMMPS, and the ReaxFF force field is used. The force field parameters are selected from the ReaxFF parameter set ffield.reax.SiOCH developed for the Si / O / C / H system.

[0018] Simulation parameters are set as follows: real units are used, three-dimensional periodic boundary conditions are applied, temperature is controlled by a thermostat, and the initial atomic velocity distribution is randomly generated.

[0019] In the above scheme, in step 4, the hydrolysis reaction process is analyzed by statistically analyzing the number evolution of key chemical bonds such as CO bonds and Si-O-Si bonds. By identifying and tracking the number evolution of hydrolysis intermediates, the stepwise hydrolysis mechanism of TEOS and the influence of temperature on each step of the hydrolysis reaction are revealed.

[0020] In the above scheme, the hydrolysis intermediate includes the monohydroxy intermediate C6H. 16 O4Si, dihydroxy intermediate C4H 12 O4Si and the trihydroxy intermediate C2H8O4Si. The mechanism of stepwise hydrolysis of TEOS is as follows:

[0021]

[0022]

[0023] .

[0024] In the above scheme, step 4 includes:

[0025] Step 4.1: Set the output type and frequency: output the trajectory file every 0.5 ps, the bonding information every 2.5 ps, the species analysis every 1.25 ps, and the thermodynamic quantity every 1.25 ps.

[0026] Step 4.2: Determine the hydrolysis reaction rate at different temperatures by calculating the changes in the amount of reactants TEOS and water over time;

[0027] Step 4.3: Analyze the hydrolysis reaction process and the initiation sequence of the polycondensation reaction by statistically analyzing the evolution of the number of key chemical bonds, CO bonds and Si-O-Si bonds;

[0028] Step 4.4: By identifying and tracking the quantitative evolution of hydrolysis intermediates, the stepwise hydrolysis mechanism of TEOS and the influence of temperature on each step of the hydrolysis reaction are revealed.

[0029] This invention eliminates the need for complex actual sol-gel experiments, overcoming the limitation of existing experimental techniques that struggle to observe initial reaction dynamics at the atomic scale. By employing a ReaxFF-based molecular dynamics simulation method, this invention successfully simulated the initial stages of TEOS hydrolysis under different temperature and acidity conditions, revealing the influence of temperature on the CO bond breaking rate and intermediate evolution pathways at the molecular level. It also confirmed the classical theory that hydrolysis takes precedence over polymerization within the simulated timescale. This method provides a theoretical basis for guiding the synthesis process of silica aerogels and helps reduce experimental trial-and-error costs.

[0030] 1. An atomic-scale simulation framework for the TEOS hydrolysis reaction was constructed. This invention establishes a complete simulation method for the initial stage of TEOS hydrolysis by integrating Packmol model construction, ReaxFF reaction force field simulation, and multi-dimensional product analysis. This framework overcomes the limitations of traditional experimental methods in terms of spatiotemporal resolution and, for the first time, achieves atomic-scale dynamic tracking of the initial hydrolysis reaction in the sol-gel process.

[0031] 2. Molecular dynamics simulation and stepwise hydrolysis pathway analysis of the initial stage of hydrolysis were achieved. This invention successfully simulated the initial process of TEOS hydrolysis within the temperature range of 298-700K. By tracing the temporal evolution of monohydroxy, dihydroxy, and trihydroxy intermediates, the stepwise reaction mechanism of TEOS hydrolysis was revealed, and the kinetic characteristics of each step of the hydrolysis reaction were clarified.

[0032] 3. The microscopic regulatory effect of temperature on the hydrolysis reaction was revealed. The degree of hydrolysis was calculated by dividing the number of TEOS consumed by the initial number of TEOS. This invention compares simulation results at different temperatures, such as... Figure 3 As shown, at 298K, the number of TEOS decreased from the initial 100 to 84, and at 700K, the number of TEOS decreased from the initial 100 to 44, through the formula...

[0033] Degree of hydrolysis = Number of TEOS consumed / Initial number of TEOS

[0034] Calculations showed that as the temperature increased from 298K to 700K, the degree of hydrolysis increased from 16% to 56%. This finding confirms that high temperature can effectively overcome the energy barriers of each step of the hydrolysis reaction, pushing the reaction to a deeper hydrolysis stage, and quantitatively elucidates the regulatory law of temperature on the degree of hydrolysis.

[0035] 4. This invention provides an atomic-scale theoretical basis for optimizing the sol-gel process. The simulation framework established in this invention not only deepens the understanding of the initial stage of TEOS hydrolysis at the mechanistic level, but also provides predictable and interpretable theoretical guidance for the selection of temperature parameters in the sol-gel process of materials such as silica aerogels by quantifying the influence of temperature on the reaction rate and intermediate distribution, effectively reducing the cost of experimental trial and error. Attached Figure Description

[0036] Figure 1 This is a schematic diagram of the initial system constructed in the simulation of this invention;

[0037] Figure 2 This is a graph showing the change in the amount of reactants TEOS and water over time at different temperatures;

[0038] Figure 3 This is a graph showing the change in the number of key chemical bonds (CO bonds) over time at different temperatures;

[0039] Figure 4 This is a graph showing the changes of various intermediate quantities over time at different temperatures;

[0040] Figure 5 This is a distribution diagram of the equilibrium yield of hydrolysis intermediates at different temperatures. Detailed Implementation

[0041] The embodiments of the present invention will be described in detail below. Although the present invention will be described and illustrated in conjunction with some specific embodiments, it should be noted that the present invention is not limited to these embodiments. On the contrary, any modifications or equivalent substitutions made to the present invention should be covered within the scope of the claims of the present invention.

[0042] Furthermore, to better illustrate the present invention, numerous specific details are set forth in the following detailed embodiments. Those skilled in the art will understand that the present invention can be practiced without these specific details.

[0043] This invention addresses the limitation of existing experimental techniques in capturing the atomic-scale dynamic processes of the initial stage of TEOS hydrolysis by providing a method based on ReaxFF molecular dynamics simulation of the initial stage of TEOS hydrolysis. This method constructs a complex mixed system model containing TEOS, ethanol, water, and a citric acid catalyst, and uses reaction molecular dynamics simulation to systematically study the initial mechanism of the hydrolysis reaction under different temperature and acidity conditions, providing molecular-level evidence for understanding the initial steps of the sol-gel process.

[0044] This invention provides a method for simulating the initial stage of TEOS hydrolysis based on ReaxFF molecular dynamics. An initial model containing TEOS, ethanol, water, and citric acid is constructed. The model is relaxed and the reaction is simulated using reaction molecular dynamics to track the evolution of key species and chemical bonds. The focus is on the gradual occurrence of hydrolysis to reveal the hydrolysis mechanism of TEOS at the molecular level.

[0045] Further, the specific steps are as follows:

[0046] Step 1: Using Packmol software, construct an initial amorphous model containing TEOS, ethanol, water, and citric acid molecules;

[0047] Step 1.1: Set the initial molecular ratio as n(TEOS):n(EtOH):n(H2O) = 1:5:7;

[0048] Step 1.2: Set the initial density to 230 kg / m³ and the minimum interatomic distance to 1.5 Å. Randomly fill the molecules into the cubic simulation box to obtain the initial model.

[0049] Step 2: Optimize and relax the structure of the constructed initial model to obtain a stable initial configuration with reasonable energy.

[0050] Step 2.1: Minimize the energy of the model using the conjugate gradient algorithm;

[0051] Step 2.2: Perform an NVT relaxation simulation at 298K for 500 ps to bring the system to equilibrium.

[0052] Step 3: Set different temperature conditions and perform reaction molecular dynamics simulations on the equilibrium model;

[0053] Step 3.1: The simulation uses the large-scale atomic / molecular parallel simulator LAMMPS, with the ReaxFF force field selected. The force field parameters are the ReaxFF parameter set ffield.reax.SiOCH developed for the Si / O / C / H system.

[0054] Step 3.2: Set simulation parameters: Use real units, three-dimensional periodic boundary conditions, time step 0.25 fs, bond-level cutoff value 0.3, and charge balance QEq method convergence accuracy 10⁻⁻⁴. 6 The temperature is controlled by a Berendsen thermostat with a damping constant of 25 fs.

[0055] Step 3.3: Linearly heat the system from 298 K to the target temperature within 10 ps, ​​with the target temperatures set to 400, 500, 600, and 700 K respectively;

[0056] Step 3.4: Perform isothermal reaction simulations at each target temperature for 1000 ps. The initial atomic velocities are randomly generated by the Maxwell-Boltzmann distribution to ensure statistical reliability.

[0057] Step 4: Output and analyze the trajectory files, bonding information, species information, and thermodynamic quantities generated during the reaction simulation process;

[0058] Step 4.1: Set the output type and frequency: output the trajectory file every 0.5 ps, the bonding information every 2.5 ps, the species analysis every 1.25 ps, and the thermodynamic quantity every 1.25 ps.

[0059] Step 4.2: Determine the hydrolysis reaction rate at different temperatures by calculating the changes in the amount of reactants TEOS and water over time;

[0060] Step 4.3: Analyze the hydrolysis reaction process and the initiation sequence of the polycondensation reaction by statistically analyzing the evolution of the number of key chemical bonds, CO bonds and Si-O-Si bonds;

[0061] Step 4.4: By identifying and tracking the quantitative evolution of hydrolysis intermediates, the stepwise hydrolysis mechanism of TEOS and the influence of temperature on each step of the hydrolysis reaction are revealed.

[0062] Step 5: Based on the simulation results, analyze the influence of temperature and acidity on the initial stage of TEOS hydrolysis and determine the optimal range of hydrolysis reaction conditions.

[0063] Furthermore, the evolution of TEOS hydrolysis intermediates at different temperatures was obtained through simulation, including the monohydroxy intermediate C6H. 16 O4Si and dihydroxy intermediate C4H 12 O4Si showed a trend of first increasing and then decreasing, with the peak time appearing earlier as the temperature increased; the trihydroxy intermediate C2H8O4Si continued to increase to a steady state during the simulation time, and its equilibrium yield increased significantly with increasing temperature, dominating at 700 K.

[0064] Furthermore, by statistically analyzing the changes in the number of Si-O-Si bonds at different temperatures, it was confirmed that the number of Si-O-Si bonds remained stable at around 400 within the simulated timescale, with no net increase. This verifies that the hydrolysis reaction takes precedence over the polycondensation reaction on the timescale, and the polycondensation reaction was not initiated under the simulated conditions.

[0065] Example 1

[0066] The following example illustrates the application of this method, including the following steps:

[0067] Step 1: Using Packmol software, a multi-component amorphous initial model was constructed using tetraethyl orthosilicate (TEOS), ethanol, water, and citric acid as raw materials. The initial molecular ratio was set to n(TEOS):n(EtOH):n(H2O) = 1:5:7. Specifically, 100 TEOS molecules, 500 ethanol molecules, and 700 water molecules were set. The initial density was set to 230 kg / m³. 3 This density is close to the bulk density of typical silica aerogels. During the filling process, the minimum interatomic distance was set to 1.5 Å to ensure no abnormal atomic overlap. After construction, the initial configuration was verified. Atomic spacing calculations showed that all atom pairs were more than 1.5 Å apart, with no abnormal overlap; the number of initial bonds matched the theoretical value, proving that no accidental bond breakage occurred during the filling process.

[0068] Step 2: Import the constructed initial model into LAMMPS. First, the conjugate gradient algorithm is used for energy minimization to eliminate local high-energy regions in the initial configuration, causing the system potential energy to converge to a local minimum. After approximately 200 conjugate gradient iterations, the system reaches a stable local minimum energy state. After energy minimization, a 500 ps NVT relaxation simulation is performed at 298 K. A Berendsen thermostat is used for temperature control, with a damping constant set to 25 fs. Relaxation allows the system to reach equilibrium at the target temperature, providing a reasonable initial configuration for subsequent reaction simulations.

[0069] Step 3: Starting from the equilibrium configuration, perform molecular dynamics simulations of the reaction. The simulation uses the Reax / c module in LAMMPS software, with the parameter set ffield.reax.SiOCH. This force field was obtained by Mueller et al. based on density functional theory calculations and has been successfully applied to the simulation of pyrolysis and oxidation reactions of various silicon-containing compounds.

[0070] The simulation parameters were set as follows: real units were used, with three-dimensional periodic boundary conditions and a time step of 0.25 fs to ensure effective capture of chemical reaction details while maintaining energy conservation. A bond-level cutoff value of 0.3 was set to determine the formation and breaking of chemical bonds. The charge balance was simulated using the QEq method with a convergence accuracy of 10⁻⁶. -6 .

[0071] The simulation process consisted of two stages: heating and isothermal control. First, the system was linearly heated from 298 K to the target temperature within 10 ps. Then, an isothermal reaction simulation was performed at the target temperature for 1000 ps. To systematically study the effect of temperature on the hydrolysis reaction, five target temperatures were set: 298, 400, 500, 600, and 700 K, with 298 K serving as the control group at room temperature. The temperature change rate and isothermal time corresponding to each target temperature are shown in Table 1.

[0072] Table 1 Temperature change rate and isothermal time for each target temperature

[0073]

[0074] Step 4: To track the evolution of chemical bonds and species changes during the reaction process, set up multiple data output methods. The trajectory file is output every 0.5 ps, the bonding information is output every 2.5 ps, the species analysis is output every 1.25 ps, and the thermodynamic quantities are output every 1.25 ps.

[0075] The hydrolysis rate at different temperatures was determined by calculating the changes in the amounts of reactants TEOS and water over time.

[0076] By identifying and tracking the quantitative evolution of hydrolysis intermediates, this study reveals the stepwise hydrolysis mechanism of TEOS and the influence of temperature on each step of the hydrolysis reaction. The hydrolysis intermediates include the monohydroxy intermediate C6H. 16 O4Si, dihydroxy intermediate C4H 12 O4Si and the trihydroxy intermediate C2H8O4Si.

[0077] Step 5: Based on the above analysis, the TEOS hydrolysis reaction under citric acid catalysis exhibits a clear stepwise hydrolysis characteristic. Increased temperature promotes TEOS hydrolysis, causing the hydrolysis intermediate to transform into the highly reactive trihydroxy form. Within this simulation timescale, the number of Si-O-Si bonds remains stable, confirming that hydrolysis preferentially precedes polymerization. These simulation results reveal the dynamic mechanism of the initial stage of TEOS hydrolysis at the atomic scale, providing a theoretical basis for understanding the sol-gel process and optimizing aerogel preparation technology.

[0078] After screening the simulation results at different temperatures, the optimal parameter range for promoting the deep hydrolysis of TEOS can be determined: simulation at higher temperatures (such as 500~700 K) is conducive to generating high concentrations of trihydroxy reactive intermediates, providing abundant reaction sites for subsequent polycondensation reactions.

[0079] Figure 1 These are initial structural diagrams for the hydrolysis reaction simulation, where (a) is a three-dimensional structural diagram of the simulation box, and (b) is the molecular structure of TEOS.

[0080] Figure 2 The graph shows the changes in the amount of reactants TEOS and water over time at different temperatures. As the temperature increases, the consumption rate of both TEOS and water increases significantly, indicating that the hydrolysis reaction is more complete at high temperatures.

[0081] Figure 3 The graph shows the change in the number of key chemical bonds (CO bonds) over time at different temperatures. Temperature has a significant effect on the breaking rate of CO bonds, and the positive correlation between the breaking rate and temperature confirms that increasing the temperature effectively promotes the hydrolysis of ethoxy groups and accelerates the hydrolysis reaction process.

[0082] Figure 4 This is a graph showing the change in the quantity of each intermediate over time at different temperatures, with the monohydroxy intermediate C6H... 16 O4Si exhibits a trend of first increasing and then decreasing at all temperatures, consistent with intermediate kinetics; its formation rate significantly accelerates with increasing temperature. The dihydroxy intermediate C4H... 12 The evolution of O4Si also follows a pattern of initial increase followed by decrease, but the peak time lags significantly behind that of the monohydroxy intermediate, directly reflecting the gradual progression of the hydrolysis reaction. For the trihydroxy intermediate C2H8O4Siii, the product quantity rapidly increases from 0 at all temperatures within the range of 0–200 ps, ​​indicating that the triple hydrolysis reaction is efficiently triggered in the early stages of the simulation. In the 200–400 ps stage, the product quantity enters a period of fluctuating growth, with more dramatic fluctuations at higher temperatures, reflecting the dynamic balance between product formation and subsequent transformation at high temperatures. After 600 ps, ​​it gradually approaches a steady state.

[0083] Figure 5 This is a distribution chart of the equilibrium yield of hydrolysis intermediates at different temperatures, which visually quantifies the effect of temperature on the distribution of intermediates. As the temperature increases from 298 K to 700 K, the yield of the monohydroxy intermediate C6H... 16 O4Si, dihydroxy intermediate C4H 12The equilibrium yields of O4Si and the trihydroxy intermediate C2H8O4Si both showed a monotonically increasing trend, indicating that high temperature can effectively overcome the energy barriers of each hydrolysis step, thus accelerating the hydrolysis process of TEOS. The above description is merely a preferred embodiment of the present invention and is not intended to limit the invention. Any modifications, equivalent substitutions, or improvements made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. A method for simulating the initial stage of TEOS hydrolysis based on ReaxFF molecular dynamics, characterized in that: Includes the following steps: Step 1: Using Packmol software, construct an initial amorphous model containing TEOS, ethanol, water, and citric acid molecules, where the molecular ratio of tetraethyl orthosilicate (TEOS), ethanol, and water is 1:(4~6):(6~8), and the initial density of the system is 200~250 kg / m³. 3 ; Step 2: Optimize and relax the structure of the constructed initial model to obtain a stable initial configuration with reasonable energy. Step 3: Using the ReaxFF force field, perform reaction molecular dynamics simulations on the equilibrium model under at least two different temperature conditions in the range of 298 K to 700 K; Step 4: Output and analyze the trajectory files, bonding information, species information and thermodynamic quantities in the reaction simulation process, including reactant consumption analysis, key chemical bond evolution analysis and hydrolysis intermediate evolution analysis. Step 5: Based on the simulation results, analyze the influence of temperature on the initial stage of TEOS hydrolysis and determine the optimal range of hydrolysis reaction conditions.

2. The method according to claim 1, characterized in that: In step 1, the initial molecular ratio is set as n(TEOS):n(EtOH):n(H2O)=1:5:7, where EtOH represents ethanol, and the initial density is set as 230 kg / m³.

3. The method according to claim 2, characterized in that: In step 2, the conjugate gradient algorithm is used to minimize the energy of the model so that the system reaches an equilibrium state.

4. The method according to claim 2, characterized in that: In step 3, the simulation uses the large-scale molecular parallel simulator LAMMPS and the ReaxFF force field. The force field parameters are selected from the ReaxFF parameter set ffield.reax.SiOCH developed for the Si / O / C / H system. Simulation parameters are set as follows: real units are used, three-dimensional periodic boundary conditions are applied, temperature is controlled by a thermostat, and the initial atomic velocity distribution is randomly generated.

5. The method according to claim 2, characterized in that: In step 4, the hydrolysis reaction process is analyzed by statistically analyzing the number evolution of key chemical bonds, CO bonds and Si-O bonds. By identifying and tracking the number evolution of hydrolysis intermediates, the stepwise hydrolysis mechanism of TEOS and the influence of temperature on each step of the hydrolysis reaction are revealed.

6. The method according to claim 5, characterized in that: The hydrolysis intermediate includes the monohydroxy intermediate C6H. 16 O4Si, dihydroxy intermediate C4H 12 O4Si and the trihydroxy intermediate C2H8O4Si. The mechanism of stepwise hydrolysis of TEOS is as follows: 。 7. The method according to claim 1, characterized in that: Step 4 includes: Step 4.1: Set the output type and frequency: output the trajectory file every 0.5 ps, the bonding information every 2.5 ps, the species analysis every 1.25 ps, and the thermodynamic quantity every 1.25 ps. Step 4.2: Determine the hydrolysis reaction rate at different temperatures by calculating the changes in the amount of reactants TEOS and water over time; Step 4.3: Analyze the hydrolysis reaction process and the initiation sequence of the polycondensation reaction by statistically analyzing the evolution of the number of key chemical bonds, CO bonds and Si-O bonds; Step 4.4: By identifying and tracking the quantitative evolution of hydrolysis intermediates, the stepwise hydrolysis mechanism of TEOS and the influence of temperature on each step of the hydrolysis reaction are revealed.

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