Isotope molecular probe reaction mechanism tracking method based on ReaxFF reaction force field

Abstract

An isotope molecular probe reaction mechanism tracking method based on a ReaxFF reaction force field comprises the steps that a ReaxFF reaction force field file is modified according to the property of isotopes, and isotope elements are added into the ReaxFF reaction force field file; adding isotope molecules into the simulation system to form a periodic structure; performing structure optimization and dynamic simulation on the whole simulation system to minimize the system energy of the simulation system; relaxation equilibrium and reaction kinetics simulation is carried out based on an energy minimization simulation system; and performing analysis based on a result derived after simulation to realize isotope tracking visualization, and determining a reaction mechanism. According to the method, simulation of the coal spontaneous combustion process can be realized, oxygen atom sources of carbon and oxygen gas generated in the coal spontaneous combustion process are effectively distinguished on the basis of combining experiments, and conversion paths of oxygen-containing groups of coal and oxygen atoms in oxygen are visualized; reliable data analysis and theoretical guidance are provided for researching reaction details in the coal oxidation process and revealing the reaction mechanism of the coal spontaneous combustion process.

Description

Technical Field

[0001] The invention belongs to the field of isotope tracing and molecular dynamics, and specifically relates to a method for tracking the reaction mechanism of an isotope molecular probe based on a ReaxFF reaction force field. Background Art

[0002] Coal spontaneous combustion is one of the main natural disasters faced by coal mining. Among the 13 existing large coal bases in my country, more than 90% of the mined coal seams are prone to spontaneous combustion or self-ignition coal seams, and the disaster of coal spontaneous combustion is very serious. According to incomplete statistics, more than 100 working faces are closed due to coal spontaneous combustion in my country every year, more than 10 million tons of coal resources are burned, and the direct economic losses exceed 10 billion yuan. It is urgent to solve the problems caused by coal spontaneous combustion. In recent years, the coal-oxygen compound theory has been widely recognized, and in-depth research on the reaction details in the coal oxidation process is of great significance for the stage control and early warning of coal spontaneous combustion.

[0003] Gas products are the external manifestation of structural changes in coal oxidation and combustion. A large number of gas products (CO, CO 2 and hydrocarbons, etc.), whose concentration changes significantly with oxidation time and temperature, can intuitively reflect the oxidation characteristics of coal and is easy to monitor, and can be used as an indicator to evaluate the spontaneous combustion oxidation state of coal. However, the source of oxygen atoms generated by carbon-oxygen gas during coal spontaneous combustion is still unclear, and there is a lack of corresponding research on the conversion path of oxygen-containing groups in coal itself and oxygen atoms in oxygen. It is difficult for existing technologies to distinguish the competitive relationship between external oxygen and oxygen in coal itself. Summary of the invention

[0004] The purpose of the present invention is to provide an isotope molecular probe reaction mechanism tracking method based on the ReaxFF reaction force field. The method can simulate the coal spontaneous combustion process, effectively distinguish the source of oxygen atoms in the carbon-oxygen gas generated during the coal spontaneous combustion process on the basis of combined experiments, and visualize the conversion path of the oxygen-containing groups in the coal itself and the oxygen atoms in the oxygen, so as to provide reliable data analysis and theoretical guidance for studying the reaction details in the coal oxidation process and revealing the reaction mechanism of the coal spontaneous combustion process.

[0005] To achieve the above-mentioned object of the invention, the present invention provides a method for tracking the reaction mechanism of isotope molecular probes based on the ReaxFF reaction force field, comprising the following steps:

[0006] (1) Modify the ReaxFF reaction force field file according to the properties of the isotope and add the isotope element to it;

[0007] (2) Adding isotope molecules into the simulation system to form a periodic structure;

[0008] (3) Structural optimization and dynamic simulation of the entire simulation system are performed to minimize the system energy of the simulation system;

[0009] (4) Relaxation and reaction kinetics simulation based on energy minimization simulation system;

[0010] (5) Analysis is performed based on the results derived after simulation to achieve isotope tracking visualization and determine the reaction mechanism.

[0011] Furthermore, in step (1), the ReaxFF reaction force field file is modified as follows: on the basis of the original ReaxFF reaction force field file, force field parameters of isotope elements are added to form a new ReaxFF reaction force field file.

[0012] Furthermore, in step (2), the simulation system is constructed as follows: a periodic box containing a main molecule and an isotope molecule is constructed in a modeling software.

[0013] Preferably, the modeling software is MS, the main molecule is a coal molecule, and the isotope molecule is isotope oxygen.

[0014] Furthermore, in step (3), the simulation system performs structural optimization and dynamic simulation, including: performing structural optimization on the constructed periodic structure using the steepest descent method or the conjugate gradient method, and performing dynamic simulation on the periodic box.

[0015] Furthermore, in step (3), the dynamic simulation process includes: using an NVT ensemble system, controlling the temperature by a Berendsen thermostat, setting the time step to 1-10 fs, and calculating for 100-200 ps.

[0016] Furthermore, in step (4), the relaxation process includes using lammps software to perform the following calculations on the simulation system: using an NVT ensemble system, the temperature is controlled by a Berendsen thermostat, and the temperature frequency is controlled using a damping coefficient of 100fs, the time step is 0.1-0.25fs, the simulation time is 40-100ps, and the temperature is 300K, so that the system reaches equilibrium.

[0017] Furthermore, in step (4), the reaction kinetics simulation process includes: after the relaxation process, performing a process with a time step of 0.1-0.25 fs, a simulation time of 200-300 ps, ​​and a temperature range of 3000-5000 K.

[0018] Furthermore, in step (5), the specific process is: using VMD software, Matlab script or VARxMD software to simultaneously compare and analyze the trajectory and product of the output file of the lammps software calculation results.

[0019] Compared with the prior art, the present invention has the following beneficial effects:

[0020] (1) The present invention provides an isotope tracing method based on the atomic scale for studying the reaction details in the coal oxidation process, the stage control and early warning of coal spontaneous combustion, which can visualize the entire reaction process and intuitively track the isotopes; the method can realize the visualization and analysis of the chemical reactions that may occur in the system containing isotopes at the mesoscopic scale and the related thermodynamic and kinetic properties;

[0021] (2) The present invention can simulate the spontaneous combustion process of coal, effectively distinguish the source of oxygen atoms in the carbon-oxygen gas generated during the spontaneous combustion of coal based on combined experiments, and visualize the transformation path between oxygen-containing groups in coal itself and oxygen atoms in oxygen, thus providing reliable data analysis and theoretical guidance for studying the reaction details in the coal oxidation process and revealing the reaction mechanism of the spontaneous combustion process of coal;

[0022] (3) The isotope molecular probe reaction mechanism tracking method based on the ReaxFF reaction force field provided by the present invention can be extended to other isotope tracking fields, providing a visual approach for studying the details of the reaction process. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] Figure 1 This is the initial molecular model diagram in the embodiment of the present invention;

[0024] Figure 2 is a schematic diagram of the simulation system in Example 1;

[0025] Figure 3 This is a schematic diagram of the simulation system of Example 1 at 0 ps;

[0026] Figure 4 Schematic diagram of the simulation system of Example 1 at 200 ps;

[0027] Figure 5 This is a schematic diagram of the simulation system of Example 1 at 470 ps;

[0028] Figure 6 is a schematic diagram of the simulation system in Example 2;

[0029] Figure 7 This is a schematic diagram of the simulation system of Example 2 at 0ps;

[0030] Figure 8 Schematic diagram of the simulation system of Example 2 at 200ps;

[0031] Fig. 9 This is a schematic diagram of the simulation system of Example 2 at 370 ps;

[0032] Fig.10 is a schematic diagram of the simulation system in Example 3;

[0033] Fig.11 This is a schematic diagram of the simulation system of Example 3 at 0ps;

[0034] Fig.12 This is a schematic diagram of the simulation system of Example 3 at 100 ps;

[0035] Fig.13 This is a schematic diagram of the simulation system of Example 3 at 270 ps;

[0036] Fig.14 is a schematic diagram of the simulation system in Example 4;

[0037] Fig.15 This is a schematic diagram of the simulation system of Example 4 at 0 ps;

[0038] Fig.16 Schematic diagram of the simulation system of Example 4 at 200ps;

[0039] Fig.17 This is a schematic diagram of the simulation system of Example 4 at 470 ps;

[0040] Fig.18 is a schematic diagram of the simulation system in Example 5;

[0041] Fig.19 This is a schematic diagram of the simulation system of Example 5 at 0 ps;

[0042] Fig. 20 This is a schematic diagram of the simulation system of Example 5 at 200 ps;

[0043] Fig.21 This is a schematic diagram of the simulation system of Example 5 at 370 ps; DETAILED DESCRIPTION

[0044] The present invention is further described in detail below in conjunction with specific embodiments.

[0045] According to one embodiment of the present invention, a method for tracking the reaction mechanism of an isotope molecular probe based on a ReaxFF reaction force field comprises the following steps:

[0046] (1) Modify the ReaxFF reaction force field file according to the properties of the isotope and add the isotope element to it;

[0047] (2) Adding isotope molecules into the simulation system to form a periodic structure;

[0048] (3) Structural optimization and dynamic simulation of the entire simulation system are performed to minimize the system energy of the simulation system;

[0049] (4) Relaxation and reaction kinetics simulation based on energy minimization simulation system;

[0050] (5) Analysis is performed based on the results derived after simulation to achieve isotope tracking visualization and determine the reaction mechanism.

[0051] According to one embodiment of the present invention, the ReaxFF reaction force field file is modified as follows: on the basis of the original ReaxFF reaction force field file, an oxygen isotope element is added 18 O force field parameters to form a new ReaxFF reaction force field file. The original ReaxFF reaction force field file includes five elements: C, H, O, N, and S. The modified ReaxFF reaction force field file includes C, H, O, N, S, 18 O these 6 elements.

[0052] It should be understood that the original ReaxFF reaction field is by no means limited to the five elements C, H, O, N, and S, and the added isotopic elements are by no means limited to 18 O, other isotope parameters can be added to other ReaxFF reaction force field files, therefore, the present invention no longer lists other modified ReaxFF reaction force field files separately.

[0053] According to one embodiment of the present invention, the simulation system is constructed as follows: a periodic box containing coal molecules and isotopic oxygen is constructed in MS, and structural optimization such as the steepest descent method, conjugate gradient method, etc. is performed to minimize its energy.

[0054] It should be understood that the modeling software used is by no means limited to MS, the periodic box can be completely composed of other main molecules and isotope molecules, and the structural optimization method adopted is by no means limited to the steepest descent method and the conjugate gradient method, and the structural optimization can be carried out in combination. Therefore, the present invention no longer lists other modeling methods separately.

[0055] According to one embodiment of the present invention, the simulation architecture optimization and dynamic simulation include: performing dynamic simulation on a periodic box, such as using an NVT ensemble system, controlling the temperature by a Berendsen thermostat, setting the time step to 1-10fs, and calculating for 100-200ps.

[0056] It should be understood that the dynamic simulation method used is by no means limited to the above method, and other settings can be used. Therefore, the present invention will not list other modeling methods separately.

[0057] According to one embodiment of the present invention, the relaxation process includes using lammps software to perform the following calculations on the simulation system: using an NVT ensemble system, the temperature is controlled by a Berendsen thermostat, and a damping coefficient of 100fs is used to control the temperature frequency, the time step is 0.1-0.25fs, the simulation time is 40-100ps, and the temperature is 300K. The relaxation method is used to make the system reach equilibrium.

[0058] It should be understood that the relaxation process is by no means limited to the above method and can be carried out in other ways. The several conditions for setting the relaxation are by no means limited to the above range. Therefore, the present invention no longer lists other relaxation methods separately.

[0059] According to one embodiment of the present invention, the reaction kinetics simulation process includes: after the relaxation process, a constant temperature process with a time step of 0.1-0.25fs, a simulation time of 200-300ps, and a temperature range of 3000-5000K is performed.

[0060] It should be understood that reaction kinetics simulation is by no means limited to the above method and can be performed in other ways. The conditions for simulation are by no means limited to the above range. Therefore, the present invention does not list other reaction kinetics simulation methods separately.

[0061] According to one embodiment of the present invention, the analysis of the exported results to achieve isotope tracking visualization and determine the reaction mechanism includes: using software such as VMD, Matlab script, VARxMD software, etc. to simultaneously compare and analyze the trajectory and products of the output file of the lammps software calculation results.

[0062] It should be understood that the analysis software and scripts used are by no means limited to the above-mentioned ones, and other software and other methods can be used. Therefore, the present invention does not list other analysis methods separately.

[0063] Example 1

[0064] A method for tracking the reaction mechanism of an isotope molecular probe based on a ReaxFF reaction force field comprises the following steps:

[0065] (1) Based on the original ReaxFF reaction force field file, oxygen isotope elements are added 18 O force field parameters to form a new ReaxFF reaction force field file. The original ReaxFF reaction force field file includes five elements: C, H, O, N, and S. The modified ReaxFF reaction force field file includes C, H, O, N, S, 18 O these 6 elements;

[0066] (2) Based on the results of the coal oxygen isotope tracing experiment, the combustion system of coal molecules and isotopic oxygen was constructed using MS, such as Figure 1The molecular structure of the coal used and the molecular structure of oxygen isotopes; the combustion equivalent ratio is determined to be 1 according to the complete reaction of the coal structure, and the AC module is used to construct a periodic box;

[0067] (3) The constructed periodic structure is optimized by the steepest descent method. The NVT ensemble system is used, the temperature is controlled by the Berendsen thermostat, the time step is set to 5 fs, and the calculation is performed for 200 ps to minimize the energy. Figure 2 This is the system that was finally optimized in MS. It can be seen from the figure that the structure of coal oxygen molecules is reasonable, and the oxygen atoms in the coal structure and the oxygen atoms in the external oxygen can be clearly distinguished, which provides an initial structure for the subsequent reaction kinetics simulation;

[0068] (4) Reaction kinetics calculations were performed in the lammps software, using an NVT ensemble system, the temperature was controlled by a Berendsen thermostat, and the temperature frequency was controlled using a damping coefficient of 100 fs, a time step of 0.1 fs, a simulation time of 40 ps, ​​and a temperature of 300 K to allow the system to reach equilibrium; after the relaxation process, a heating process was performed with a time step of 0.1 fs, a simulation time of 470 ps, ​​and a temperature range of 300 K-5000 K;

[0069] (5) The calculated output file is post-processed and imported into VMD for visual tracking. The product and trajectory analysis is performed through the tlc script, such as Figure 3-5 This is the structure after output file visualization. From the figure, we can clearly distinguish the competitive reaction process between external oxygen atoms and coal structure oxygen atoms. Figure 3-5 The macromolecules of coal structure are gradually destroyed to generate small molecular products under pyrolysis and oxidation. The changes of oxygen-containing groups in coal itself, such as hydroxyl, carboxyl, aldehyde and other groups, as well as the generation of gas products can be seen. The specific reaction path of oxygen atoms can be further analyzed based on the visualization results and output files.

[0070] Example 2

[0071] A method for tracking the reaction mechanism of an isotope molecular probe based on a ReaxFF reaction force field comprises the following steps:

[0072] (1) Based on the original ReaxFF reaction force field file, oxygen isotope elements are added 18 O force field parameters to form a new ReaxFF reaction force field file. The original ReaxFF reaction force field file includes five elements: C, H, O, N, and S. The modified ReaxFF reaction force field file includes C, H, O, N, S, 18 O these 6 elements;

[0073] (2) Based on the results of the coal oxygen isotope tracing experiment, the combustion system of coal molecules and isotopic oxygen was constructed using MS, such as Figure 1 The molecular structure of the coal used and the molecular structure of oxygen isotopes; the combustion equivalent ratio is determined to be 2 according to the oxygen-enriched combustion reaction of the coal structure, and the AC module is used to construct a periodic box;

[0074] (3) The conjugate gradient method is used to optimize the constructed periodic structure. At the same time, the NVT ensemble system is used, the temperature is controlled by the Nose thermostat, the time step is set to 1fs, and the calculation is 100ps to minimize the energy; Figure 6 For the system finally optimized in MS, it can be seen that the structure of coal oxygen molecules is reasonable, and the oxygen atoms in the coal structure and the oxygen atoms in the external oxygen can be clearly distinguished, which provides the initial structure for the subsequent reaction kinetics simulation;

[0075] (4) Reaction kinetics calculations were performed in the lammps software, using an NVT ensemble system, the temperature was controlled by a Berendsen thermostat, and the temperature frequency was controlled using a damping coefficient of 100 fs, a time step of 0.1 fs, a simulation time of 50 ps, ​​and a temperature of 300 K. The relaxation method was used to allow the system to reach equilibrium; after the relaxation process, a heating process was performed with a time step of 0.1 fs, a simulation time of 370 ps, ​​and a temperature range of 300 K-4000 K.

[0076] (5) The calculated output file is post-processed and imported into the Matlab script for visual tracking, such as Figure 7-9 This is the structure after output file visualization. From the figure, we can clearly distinguish the competitive reaction process between external oxygen atoms and coal structure oxygen atoms. Figure 7-9 The macromolecules of coal structure are gradually destroyed to generate small molecular products under pyrolysis and oxidation. The changes of oxygen-containing groups in coal itself, such as hydroxyl, carboxyl, aldehyde and other groups, as well as the generation of gas products can be seen. The specific reaction path of oxygen atoms can be further analyzed based on the visualization results and output files.

[0077] Example 3

[0078] A method for tracking the reaction mechanism of an isotope molecular probe based on a ReaxFF reaction force field comprises the following steps:

[0079] (1) Based on the original ReaxFF reaction force field file, oxygen isotope elements are added 18 O force field parameters to form a new ReaxFF reaction force field file. The original ReaxFF reaction force field file includes five elements: C, H, O, N, and S. The modified ReaxFF reaction force field file includes C, H, O, N, S, 18 O these 6 elements;

[0080] (2) Based on the results of the coal oxygen isotope tracing experiment, the combustion system of coal and isotope oxygen was constructed using MS, such as Figure 1 The molecular structure of the coal used and the molecular structure of oxygen isotopes; the combustion equivalent ratio is determined to be 0.5 according to the oxygen-poor combustion reaction, and the AC module is used to construct a periodic box;

[0081] (3) The constructed periodic structure is optimized by the steepest descent method and the conjugate gradient method. At the same time, the NVT ensemble system is used, the temperature is controlled by the Nose thermostat, the time step is set to 1fs, and the calculation is 200ps to minimize the energy, such as Fig.10 For the system finally optimized in MS, it can be seen that the structure of coal oxygen molecules is reasonable, and the oxygen atoms in the coal structure and the oxygen atoms in the external oxygen can be clearly distinguished, which provides the initial structure for the subsequent reaction kinetics simulation;

[0082] (4) Reaction kinetics calculations were performed in the lammps software, using an NVT ensemble system, the temperature was controlled by a Berendsen thermostat, and the temperature frequency was controlled using a damping coefficient of 100 fs, a time step of 0.1 fs, a simulation time of 50 ps, ​​and a temperature of 300 K to allow the system to reach equilibrium; after the relaxation process, a heating process was performed with a time step of 0.1 fs, a simulation time of 270 ps, ​​and a temperature range of 300 K-3000 K;

[0083] (5) The calculated output file is post-processed and imported into VARxMD for visual tracking, such as Figure 11-13 This is the structure after output file visualization. From the figure, we can clearly distinguish the competitive reaction process between external oxygen atoms and coal structure oxygen atoms. Figure 11-13 The macromolecules of coal structure are gradually destroyed to generate small molecular products under pyrolysis and oxidation. The changes of oxygen-containing groups in coal itself, such as hydroxyl, carboxyl, aldehyde and other groups, as well as the generation of gas products can be seen. The specific reaction path of oxygen atoms can be further analyzed based on the visualization results and output files.

[0084] Example 4

[0085] A method for tracking the reaction mechanism of an isotope molecular probe based on a ReaxFF reaction force field comprises the following steps:

[0086] (1) On the basis of the original ReaxFF reaction force field file, the force field parameters of the tritium isotope element D are added to form a new ReaxFF reaction force field file. Specifically, the original ReaxFF reaction force field file includes five elements, namely C, H, O, N, and S. After modification, it includes six elements, namely C, H, O, N, S, and D.

[0087] (2) Based on the results of coal hydrogen isotope (coal tritium) tracing experiments, MS was used to construct a combustion system of coal molecules and tritium gas, such as Figure 1 The molecular structure of coal and tritium molecules (D 2 ) structure. According to the coal-hydrogen co-combustion reaction, the combustion equivalence ratio is determined to be 1, and the AC module is used to construct a periodic box;

[0088] (3) The constructed periodic structure is optimized by the steepest descent method, and the NVT ensemble system is used. The temperature is controlled by the Berendsen thermostat, the time step is set to 10fs, and the calculation is 300ps to minimize the energy. Fig.14 For the system that was finally optimized in MS, it can be seen that the molecular structure of coal tritium is reasonable, and the hydrogen atoms in the coal structure and the hydrogen atoms in the external hydrogen can be clearly distinguished, which provides the initial structure for the subsequent reaction kinetics simulation;

[0089] (4) Reaction kinetics calculations were performed in the lammps software, using an NVT ensemble system, the temperature was controlled by a Berendsen thermostat, and the temperature frequency was controlled using a damping coefficient of 100 fs, a time step of 0.25 fs, a simulation time of 40 ps, ​​and a temperature of 300 K. The relaxation method was used to allow the system to reach equilibrium; after the relaxation process, a heating process was performed with a time step of 0.25 fs, a simulation time of 470 ps, ​​and a temperature range of 300 K-5000 K.

[0090] (5) The calculated output files are post-processed and imported into VMD for visual tracking, and the products and trajectories are analyzed by VARxMD, such as Figure 15-17 This is the structure after output file visualization. From the figure, we can clearly distinguish the competitive reaction process between external hydrogen atoms and coal structure hydrogen atoms. Figure 15-17 The coal structure macromolecules are gradually destroyed under pyrolysis and hydrogen abstraction, but the reaction is not so intense and the degree of destruction is small. They are mainly decomposed under pyrolysis and the side chains fall off under hydrogen abstraction. It can be seen that the hydrogen-containing groups of the coal itself, such as hydroxyl, carboxyl, aldehyde and other groups, have changed before and after, as well as the generation of gas products. The specific reaction path of hydrogen atoms can be further analyzed based on the visualization results and output files.

[0091] Example 5

[0092] A method for tracking the reaction mechanism of an isotope molecular probe based on a ReaxFF reaction force field comprises the following steps:

[0093] (1) Based on the original ReaxFF reaction force field file, nitrogen isotope elements are added 15N force field parameters to form a new ReaxFF reaction force field file. The original ReaxFF reaction force field file includes five elements: C, H, O, N, and S. The modified ReaxFF reaction force field file includes C, H, O, N, S, 15 N these 6 elements;

[0094] (2) Based on the results of the coal nitrogen isotope tracing experiment, MS was used to construct the relationship between coal molecules and ammonia (including 15 N) pyrolysis system, such as Figure 1 The molecular structure of the coal used and the ammonia molecule (containing 15 N) structure. According to the coal-ammonia co-pyrolysis reaction, the ratio of coal molecules to ammonia molecules is determined to be 1:50, and the AC module is used to construct a periodic box;

[0095] (3) The constructed periodic structure is optimized by the steepest descent method, and the NVT ensemble system is used. The temperature is controlled by the Nose thermostat, the time step is set to 1fs, and the calculation is 500ps to minimize the energy. Fig.18 For the system finally optimized in MS, it can be seen that the molecular structure of coal-ammonia is reasonable, and the nitrogen atoms in the coal structure and the nitrogen atoms in the external ammonia can be clearly distinguished, which provides the initial structure for the subsequent reaction kinetics simulation;

[0096] (4) Reaction kinetics calculations were performed in the lammps software, using an NVT ensemble system, the temperature was controlled by a Berendsen thermostat, and the temperature frequency was controlled using a damping coefficient of 100 fs, a time step of 0.1 fs, a simulation time of 40 ps, ​​and a temperature of 300 K. The relaxation method was used to allow the system to reach equilibrium. After the relaxation process, a heating process was performed with a time step of 0.1 fs, a simulation time of 370 ps, ​​and a temperature range of 300 K-4000 K.

[0097] (5) The calculated output file is post-processed and imported into VMD for visual tracking. The product and trajectory analysis is performed through VMD, such as Figure 19-21 This is the structure after output file visualization. From the figure, we can clearly distinguish the competitive reaction process between external nitrogen atoms and coal structure nitrogen atoms. Figure 19-21 The macromolecules of the coal structure are gradually destroyed under pyrolysis to generate small molecular products. The changes in the nitrogen-containing structure of the coal itself and the generation of gas products can be seen. The specific reaction path of the nitrogen atom can be further analyzed based on the visualization results and output files.

Claims

1. A method for tracking the reaction mechanism of isotope molecular probes based on ReaxFF reaction force field, characterized in that: The following steps are involved: (1) Modify the ReaxFF reaction force field file according to the properties of the isotope and add the isotope element to it; (2) Adding isotope molecules into the simulation system to form a periodic structure; (3) Structural optimization and dynamic simulation of the entire simulation system are performed to minimize the system energy of the simulation system; (4) Relaxation and reaction kinetics simulation based on energy minimization simulation system; (5) Analysis is performed based on the results derived after simulation to achieve isotope tracking visualization and determine the reaction mechanism.

2. The method for tracking the reaction mechanism of isotope molecular probes based on the ReaxFF reaction force field according to claim 1, characterized in that: In step (1), the ReaxFF reaction force field file is modified as follows: on the basis of the original ReaxFF reaction force field file, force field parameters of isotope elements are added to form a new ReaxFF reaction force field file.

3. The method for tracking the reaction mechanism of isotope molecular probes based on ReaxFF reaction force field according to claim 1 or 2, characterized in that: In step (2), the simulation system is constructed as follows: a periodic box containing a main molecule and an isotope molecule is constructed in a modeling software.

4. The method for tracking the reaction mechanism of isotope molecular probes based on ReaxFF reaction force field according to claim 3, characterized in that: The modeling software is MS, the main molecule is the coal molecule, and the isotope molecule is the isotope oxygen.

5. The method for tracking the reaction mechanism of isotope molecular probes based on ReaxFF reaction force field according to claim 3, characterized in that: In step (3), the simulation system performs structural optimization and dynamic simulation, including: using the steepest descent method or the conjugate gradient method to perform structural optimization on the constructed periodic structure, and performing dynamic simulation on the periodic box.

6. The method for tracking the reaction mechanism of isotope molecular probes based on ReaxFF reaction force field according to claim 5, characterized in that: In step (3), the dynamic simulation process includes: using an NVT ensemble system, controlling the temperature by a Berendsen thermostat, setting the time step to 1-10 fs, and calculating for 100-200 ps.

7. The method for tracking the reaction mechanism of isotope molecular probes based on ReaxFF reaction force field according to claim 1 or 2, characterized in that: In step (4), the relaxation process includes using lammps software to perform the following calculations on the simulation system: using an NVT ensemble system, the temperature is controlled by a Berendsen thermostat, and the temperature frequency is controlled using a damping coefficient of 100fs, the time step is 0.1-0.25fs, the simulation time is 40-100ps, and the temperature is 300K, so that the system reaches equilibrium.

8. The method for tracking the reaction mechanism of isotope molecular probes based on ReaxFF reaction force field according to claim 1 or 2, characterized in that: In step (4), the reaction kinetics simulation process includes: after the relaxation process, a process with a time step of 0.1-0.25fs, a simulation time of 200-300ps, and a temperature range of 3000-5000K is performed.

9. The method for tracking the reaction mechanism of isotope molecular probes based on ReaxFF reaction force field according to claim 1 or 2, characterized in that: In step (5), the specific process is: using VMD software, Matlab script or VARxMD software to compare and analyze the trajectory and product of the output file of the lammps software calculation results at the same time.

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