A molecular dynamics simulation method for gas leakage in metal micro-cracks
By constructing a nanoscale gas leakage interface model of metal microcracks using molecular dynamics simulation methods, the problem of traditional methods being unable to simulate microscopic gas leakage is solved, thereby improving the performance and reliability of metal seals.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Patents(China)
- Current Assignee / Owner
- BEIJING INST OF TECH
- Filing Date
- 2024-06-20
- Publication Date
- 2026-05-19
AI Technical Summary
Existing technologies are insufficient to effectively describe and analyze the leakage behavior of gas in metal microcracks at the microscale. Traditional experimental methods and fluid dynamics simulations cannot accurately simulate the gas leakage mechanism of microcracks in metal seals, affecting sealing performance, lifespan, and reliability.
A nanoscale gas leakage interface model of metal microcracks was constructed using molecular dynamics simulation. The leakage law and mechanism of gas in microcracks were studied through molecular dynamics simulation. A periodic supercell model was constructed using bcc iron unit cells, and some iron atoms were deleted to form hollow microchannels. Combined with energy minimization treatment and NVT ensemble simulation, the concentration of gas molecules and leakage rate were analyzed.
It enables the analysis of gas molecule leakage patterns in microcracks at the nanoscale, promoting the optimization of metal seal manufacturing, improving product performance, lifespan and reliability, and features high computational efficiency and low simulation cost.
Smart Images
Figure CN118711681B_ABST
Abstract
Description
Technical Field
[0001] This invention relates to the field of molecular simulation technology, and in particular to a molecular dynamics simulation method for gas leakage in metal microcracks. Background Technology
[0002] Seals are critical components of precision instruments and equipment such as rotating machinery and power machinery. For precision metal seals, defects in the metal crystal structure, residual stress, and working stress can easily induce microcracks, leading to gas leakage, compromising sealing performance, and consequently adversely affecting the product's performance, lifespan, and reliability. Therefore, studying the leakage behavior and laws of gas in microcracks of metal seals has important theoretical guiding significance for optimizing the performance of metal seals.
[0003] Unlike gas flow in macroscopic cracks, when the spatial scale of microcracks decreases to near the mean free path of gas molecules, the rarefaction and compressibility effects of gas become increasingly prominent. Gas leakage in microcracks tends towards molecular flow and transitional flow states, rendering the fluid continuum assumption invalid, and thus the traditional Navier-Stokes equations based on this assumption fail. Furthermore, leaking gas in microcracks exhibits viscous dissipation, surface effects, and nonlinear effects, determining the complexity of its leakage behavior. Therefore, traditional experimental methods and fluid dynamics simulations struggle to effectively describe, analyze, and explain the motion mechanism of leaking gas in microcracks at the microscopic scale.
[0004] Molecular dynamics simulation serves as a bridge between the microstructure and macroscopic properties of materials. It can simulate both the static structure and dynamic behavior of molecules at the atomic and molecular scales. Molecular dynamics can be used to simulate the dynamic diffusion behavior of gas within microcracks over minute timescales. Therefore, establishing an interface model for gas leakage in metal microcracks from a microscopic perspective and using molecular dynamics simulations to study the leakage patterns and mechanisms will provide theoretical support for optimizing the manufacturing of metal seals and is a crucial measure to improve the sealing performance, lifespan, and reliability of precision instruments. Summary of the Invention
[0005] To overcome the shortcomings of existing technologies, this invention provides a molecular dynamics simulation method for gas leakage in metal microcracks, the specific technical solution of which is as follows:
[0006] (1) Modeling of metal microcracks
[0007] A periodic supercell iron model of a×b×c is constructed based on bcc iron cell; along the extension path of the microcrack in the depth direction, some iron atoms are deleted in the supercell iron model according to the size and shape of the microcrack to obtain a microcrack iron model with a pre-set hollow microchannel.
[0008] (2) Gas Modeling and Relaxation
[0009] The gas molecules after energy minimization are placed into a periodic box to obtain a periodic gas model, and then the periodic gas model is subjected to energy minimization. The gas model after energy minimization is then subjected to molecular dynamics simulation of the NVT ensemble to obtain a relaxed gas model.
[0010] (3) Leakage interface modeling and relaxation
[0011] A vacuum layer and an isolation layer are constructed, and then the vacuum layer, the microcracked iron model, the relaxed gas model, and the isolation layer are sequentially spliced together. The atomic positions of the iron atoms are fixed to obtain a layered gas leakage interface model. The gas leakage interface model is subjected to energy minimization processing, and then molecular dynamics simulation of the NVT ensemble is performed to obtain the molecular dynamics trajectory file.
[0012] (4) Analysis of simulation results
[0013] Based on molecular dynamics trajectory files, the changes in gas molecule concentration distribution, radial distribution, and mean square displacement are analyzed. The leakage rate of gas in the microcrack is calculated using the formula qt = P1V - P2V, where q represents the leakage rate of gas in the microcrack, t represents the leakage time, V represents the gas volume, P1 represents the gas pressure before leakage, and P2 represents the gas pressure after leakage.
[0014] In step (1), the bcc iron cell is: JCPDS No. 6-0696; the metal layer wall thickness of the hollow microchannel is...
[0015] In step (2), the gas includes one or more of the following: helium, argon, neon, nitrogen, hydrogen, oxygen, carbon dioxide, carbon monoxide, water vapor, ammonia, methane, ethane, propane, butane, ethylene, propylene, and butene.
[0016] In step (2), the a, b, α, β, and γ of the periodic gas model are consistent with the supercell iron model in step (1), and the c of the periodic gas model is determined by the gas pressure, which is 0.01-70 atm.
[0017] In step (2), the molecular dynamics simulation force field includes one of the following: COMPASS force field, cvff force field, and pcff force field. The temperature is controlled by the Nosé-Hoover hot bath method, and the temperature, dynamic time, and time step are 73.15-673.15K, 2000-40000ps, and 0.5-2fs, respectively.
[0018] In steps (2) and (3), the energy minimization process comprehensively utilizes the steepest descent method, the conjugate gradient method, and the Newton-Raphson iteration method. The force fields used include one of the COMPASS force field, the cvff force field, and the pcff force field. The convergence thresholds for the maximum energy change, the maximum force, and the maximum displacement are 2 × 10⁻⁶. -5 -0.001 kcal / mol
[0019] In step (3), the isolation layer is a periodic supercell iron model constructed based on bcc iron unit cells. The thickness c of the isolation layer includes 1-9 layers of iron atoms, and the a, b, α, β, and γ of the isolation layer are consistent with the microcrack iron model. The vacuum layer does not contain gas molecules, and the a, b, α, β, and γ of the vacuum layer are consistent with the microcrack iron model. The thickness c of the vacuum layer is... vacuum For the thickness c of the periodic gas model gas 0.2-2 times.
[0020] In step (3), the molecular dynamics simulation force field includes one of the following: COMPASS force field, cvff force field, and pcff force field. The temperature is controlled by the Nosé-Hoover hot bath method, and the simulation temperature, dynamic time, and time step are set to 73.15-673.15K, 100-3000ps, and 0.1-2fs, respectively.
[0021] Compared with the prior art, the present invention has the following advantages: The patented method can construct a nanoscale microcrack gas leakage interface model, analyze the leakage law of gas molecules in microcracks from the nanoscale, obtain the intrinsic relationship between microcrack size, structure and gas leakage evolution, promote the manufacturing optimization of metal seals, improve product performance, life and reliability, and also has the advantages of high computational efficiency and low simulation cost, which helps to promote the simulation method. Attached Figure Description
[0022] Figure 1 A schematic flowchart of a molecular dynamics simulation method for gas leakage in metal microcracks provided by the present invention;
[0023] Figure 2 This is a schematic cross-sectional view of the microcrack model containing hollow microchannels of the present invention;
[0024] Figure 3 This is a schematic diagram of the metal microcrack gas leakage interface model of the present invention;
[0025] Figure 4 shows the molecular dynamics simulation of the vacuum-iron microcrack-helium-iron isolation layer interface model provided in Embodiment 1 of the present invention at different times. The structural size of the interface model is 10.6nm×11.2nm×400nm, and the size of the hollow channel in the iron microcrack in the interface model is 9.5nm×10nm×100nm. Figure 4(a) is a simulation snapshot at t=0ps, when the gas has not yet entered the hollow microchannel of the microcrack. Figures 4(b)-(e) are simulation snapshots at t=220ps, t=400ps, t=600ps, and t=800ps, respectively. It can be seen that as time goes by, the number of helium molecules leaking into the vacuum layer through the hollow microchannel of the microcrack gradually increases. Detailed Implementation
[0026] The present invention will be further described below with reference to the accompanying drawings and embodiments, but the content of the present invention is not limited to the following embodiments.
[0027] Example 1
[0028] (1) Modeling of metal microcracks
[0029] A periodic supercell iron model of a×b×c was constructed based on a bcc iron cell. Along the depth path of the microcracks, some iron atoms were deleted from the supercell iron model according to the size and shape of the microcracks, resulting in a microcrack iron model with pre-set hollow microchannels. The bcc iron cell is JCPDS No. 6-0696, and the metal layer wall thickness of the hollow microchannels is...
[0030] (2) Gas Modeling and Relaxation
[0031] Helium molecules after energy minimization were placed in a periodic box to obtain a periodic gas model, which was then subjected to energy minimization. The gas model after energy minimization was then subjected to molecular dynamics simulation using the NVT ensemble to obtain a relaxed gas model. The a, b, α, β, and γ values of the periodic gas model were consistent with the supercell iron model in step (1), while the c value of the periodic gas model was determined by the gas pressure, which was 1 atm. The force field for the molecular dynamics simulation was the COMPASS force field, with the temperature controlled using the Nosé-Hoover hot bath method. The temperature, dynamics time, and time step were 298.15 K, 10000 ps, and 1 fs, respectively. The energy minimization process combined the steepest descent method, the conjugate gradient method, and the Newton-Raphson iteration method. The force field used was the COMPASS force field, and the convergence thresholds for the maximum energy change, maximum force, and maximum displacement were 2 × 10⁻⁶. -5 kcal / mol
[0032] (3) Leakage interface modeling and relaxation
[0033] A vacuum layer and an isolation layer were constructed, and then the vacuum layer, the microcracked iron model, the relaxed gas model, and the isolation layer were sequentially assembled, with the atomic positions of the iron atoms fixed, to obtain a layered gas leakage interface model. Energy minimization was applied to the gas leakage interface model, followed by molecular dynamics simulation using the NVT ensemble to obtain the molecular dynamics trajectory file. The energy minimization process comprehensively employed the steepest descent method, the conjugate gradient method, and the Newton-Raphson iteration method, using the COMPASS force field. The convergence thresholds for maximum energy change, maximum force, and maximum displacement were 2 × 10⁻⁶. -5 kcal / mol The isolation layer is a periodic supercellular iron model constructed based on bcc iron units. The thickness c of the isolation layer includes one layer of iron atoms. The a, b, α, β, and γ axes of the isolation layer are consistent with the microcracked iron model. The vacuum layer does not contain gas molecules. The a, b, α, β, and γ axes of the vacuum layer are consistent with the microcracked iron model. The thickness c of the vacuum layer... vacuum For the thickness c of the periodic gas model gas 0.5 times; the molecular dynamics simulation force field was the COMPASS force field, and the temperature was controlled using the Nosé-Hoover hot bath method. The simulation temperature, dynamic time, and time step were set to 298.15 K, 8000 ps, and 0.5 fs, respectively.
[0034] (4) Analysis of simulation results
[0035] Based on molecular dynamics trajectory files, the changes in gas molecule concentration distribution, radial distribution, and mean square displacement are analyzed. The leakage rate of gas in the microcrack is calculated using the formula qt = P1V - P2V, where q represents the leakage rate of gas in the microcrack, t represents the leakage time, V represents the gas volume, P1 represents the gas pressure before leakage, and P2 represents the gas pressure after leakage.
[0036] Example 2
[0037] (1) Modeling of metal microcracks
[0038] A periodic supercell iron model of a×b×c was constructed based on a bcc iron cell. Along the depth path of the microcracks, some iron atoms were deleted from the supercell iron model according to the size and shape of the microcracks, resulting in a microcrack iron model with pre-set hollow microchannels. The bcc iron cell is JCPDS No. 6-0696, and the metal layer wall thickness of the hollow microchannels is...
[0039] (2) Gas Modeling and Relaxation
[0040] Argon molecules after energy minimization were placed in a periodic box to obtain a periodic gas model, and then energy minimization was performed on the periodic gas model. Molecular dynamics simulation of the energy-minimized gas model was performed using the NVT ensemble to obtain a relaxed gas model. The a, b, α, β, and γ of the periodic gas model were consistent with the supercell iron model in step (1), and the c of the periodic gas model was determined by the gas pressure, which was 4 atm. The force field for the molecular dynamics simulation was the COMPASS force field, and the temperature was controlled using the Nosé-Hoover hot bath method. The temperature, dynamic time, and time step were 73.15 K, 20000 ps, and 0.5 fs, respectively. The energy minimization process combined the steepest descent method, the conjugate gradient method, and the Newton-Raphson iteration method. The force field used was the COMPASS force field, and the convergence thresholds for the maximum energy change, maximum force, and maximum displacement were 1 × 10⁻⁶. -4 kcal / mol
[0041] (3) Leakage interface modeling and relaxation
[0042] A vacuum layer and an isolation layer were constructed, and then the vacuum layer, the microcracked iron model, the relaxed gas model, and the isolation layer were sequentially assembled, with the atomic positions of the iron atoms fixed, to obtain a layered gas leakage interface model. Energy minimization was applied to the gas leakage interface model, followed by molecular dynamics simulation using the NVT ensemble to obtain the molecular dynamics trajectory file. The energy minimization process comprehensively employed the steepest descent method, the conjugate gradient method, and the Newton-Raphson iteration method, using the COMPASS force field. The convergence thresholds for maximum energy change, maximum force, and maximum displacement were 1 × 10⁻⁶. -4 kcal / mol The isolation layer is a periodic supercellular iron model constructed based on the bcc iron unit cell. The thickness c of the isolation layer includes two layers of iron atoms. The a, b, α, β, and γ axes of the isolation layer are consistent with the microcracked iron model. The vacuum layer does not contain gas molecules. The a, b, α, β, and γ axes of the vacuum layer are consistent with the microcracked iron model. The thickness c of the vacuum layer... vacuum For the thickness c of the periodic gas model gas The force field for the molecular dynamics simulation was the COMPASS force field, and the temperature was controlled using the Nosé-Hoover hot bath method. The simulation temperature, dynamic time, and time step were set to 73.15 K, 1000 ps, and 1 fs, respectively.
[0043] (4) Analysis of simulation results
[0044] Based on molecular dynamics trajectory files, the changes in gas molecule concentration distribution, radial distribution, and mean square displacement are analyzed. The leakage rate of gas in the microcrack is calculated using the formula qt = P1V - P2V, where q represents the leakage rate of gas in the microcrack, t represents the leakage time, V represents the gas volume, P1 represents the gas pressure before leakage, and P2 represents the gas pressure after leakage.
[0045] Example 3
[0046] (1) Modeling of metal microcracks
[0047] A periodic supercell iron model of a×b×c was constructed based on a bcc iron cell. Along the depth path of the microcracks, some iron atoms were deleted from the supercell iron model according to the size and shape of the microcracks, resulting in a microcrack iron model with pre-set hollow microchannels. The bcc iron cell is JCPDS No. 6-0696, and the metal layer wall thickness of the hollow microchannels is...
[0048] (2) Gas Modeling and Relaxation
[0049] Nitrogen molecules after energy minimization were placed in a periodic box to obtain a periodic gas model, which was then subjected to energy minimization. Molecular dynamics simulations using the NVT ensemble were performed on the energy-minimized gas model to obtain a relaxed gas model. The a, b, α, β, and γ values of the periodic gas model were consistent with the supercell iron model in step (1), while the c value of the periodic gas model was determined by the gas pressure, which was 8 atm. The force field for the molecular dynamics simulation was a cvff force field, with the temperature controlled using the Nosé-Hoover hot bath method. The temperature, dynamics time, and time step were 473.15 K, 30000 ps, and 1.5 fs, respectively. The energy minimization process combined the steepest descent method, the conjugate gradient method, and the Newton-Raphson iteration method, using a cvff force field. The convergence thresholds for the maximum energy change, maximum force, and maximum displacement were 5 × 10⁻⁶. -5 kcal / mol
[0050]
[0051] (3) Leakage interface modeling and relaxation
[0052] A vacuum layer and an isolation layer were constructed, and then the vacuum layer, the microcracked iron model, the relaxed gas model, and the isolation layer were sequentially assembled, with the atomic positions of the iron atoms fixed, to obtain a layered gas leakage interface model. Energy minimization was applied to the gas leakage interface model, followed by molecular dynamics simulation using the NVT ensemble to obtain the molecular dynamics trajectory file. The energy minimization process comprehensively utilized the steepest descent method, the conjugate gradient method, and the Newton-Raphson iteration method, using a cvff force field. The convergence thresholds for maximum energy change, maximum force, and maximum displacement were 5 × 10⁻⁶. -4 kcal / mol The isolation layer is a periodic supercellular iron model constructed based on the bcc iron unit cell. The thickness c of the isolation layer includes four layers of iron atoms. The a, b, α, β, and γ axes of the isolation layer are consistent with the microcracked iron model. The vacuum layer does not contain gas molecules. The a, b, α, β, and γ axes of the vacuum layer are consistent with the microcracked iron model. The thickness c of the vacuum layer... vacuum For the thickness c of the periodic gas model gas 1.5 times; the molecular dynamics simulation force field is a cvff force field, and the temperature is controlled by the Nosé-Hoover hot bath method. The simulation temperature, dynamic time and time step are set to 473.15K, 1200ps and 1.5fs, respectively.
[0053] (4) Analysis of simulation results
[0054] Based on molecular dynamics trajectory files, the changes in gas molecule concentration distribution, radial distribution, and mean square displacement are analyzed. The leakage rate of gas in the microcrack is calculated using the formula qt = P1V - P2V, where q represents the leakage rate of gas in the microcrack, t represents the leakage time, V represents the gas volume, P1 represents the gas pressure before leakage, and P2 represents the gas pressure after leakage.
[0055] Example 4
[0056] (1) Modeling of metal microcracks
[0057] A periodic supercell iron model of a×b×c was constructed based on a bcc iron cell. Along the depth path of the microcracks, some iron atoms were deleted from the supercell iron model according to the size and shape of the microcracks, resulting in a microcrack iron model with pre-set hollow microchannels. The bcc iron cell is JCPDS No. 6-0696, and the metal layer wall thickness of the hollow microchannels is...
[0058] (2) Gas Modeling and Relaxation
[0059] Water vapor molecules after energy minimization were placed in a periodic box to obtain a periodic gas model, and then energy minimization was performed on the periodic gas model. Molecular dynamics simulation of the energy-minimized gas model was performed using the NVT ensemble to obtain a relaxed gas model. The a, b, α, β, and γ of the periodic gas model were consistent with the supercell iron model in step (1), and the c of the periodic gas model was determined by the gas pressure, which was 16 atm. The force field for the molecular dynamics simulation was the pcff force field, and the temperature was controlled using the Nosé-Hoover hot bath method. The temperature, dynamic time, and time step were 673.15 K, 40000 ps, and 2 fs, respectively. The energy minimization process combined the steepest descent method, the conjugate gradient method, and the Newton-Raphson iteration method. The force field used was the pcff force field, and the convergence thresholds for the maximum energy change, maximum force, and maximum displacement were 0.001 kcal / mol,
[0060] (3) Leakage interface modeling and relaxation
[0061] A vacuum layer and an isolation layer were constructed, and then the vacuum layer, the microcracked iron model, the relaxed gas model, and the isolation layer were sequentially assembled, with the atomic positions of the iron atoms fixed, to obtain a layered gas leakage interface model. Energy minimization was applied to the gas leakage interface model, followed by molecular dynamics simulation using the NVT ensemble to obtain the molecular dynamics trajectory file. The energy minimization process comprehensively utilized the steepest descent method, the conjugate gradient method, and the Newton-Raphson iteration method, using a pcff force field. The convergence thresholds for maximum energy change, maximum force, and maximum displacement were 0.001 kcal / mol, respectively. The isolation layer is a periodic supercellular iron model constructed based on the bcc iron unit cell. The thickness c of the isolation layer includes eight layers of iron atoms. The a, b, α, β, and γ axes of the isolation layer are consistent with the microcracked iron model. The vacuum layer does not contain gas molecules. The a, b, α, β, and γ axes of the vacuum layer are consistent with the microcracked iron model. The thickness c of the vacuum layer... vacuum For the thickness c of the periodic gas model gas Twice that of the previous simulation; the molecular dynamics simulation force field was the pcff force field, and the temperature was controlled using the Nosé-Hoover hot bath method. The simulation temperature, dynamic time, and time step were set to 673.15 K, 1600 ps, and 2 fs, respectively.
[0062] (4) Analysis of simulation results
[0063] Based on molecular dynamics trajectory files, the changes in gas molecule concentration distribution, radial distribution, and mean square displacement are analyzed. The leakage rate of gas in the microcrack is calculated using the formula qt = P1V - P2V, where q represents the leakage rate of gas in the microcrack, t represents the leakage time, V represents the gas volume, P1 represents the gas pressure before leakage, and P2 represents the gas pressure after leakage.
Claims
1. A molecular dynamics simulation method for gas leakage in metal microcracks, characterized in that... The simulation steps are as follows: (1) Modeling of metal microcracks A periodic supercell iron model of a×b×c is constructed based on bcc iron cell; along the extension path of the microcrack in the depth direction, some iron atoms are deleted in the supercell iron model according to the size and shape of the microcrack to obtain a microcrack iron model with a pre-set hollow microchannel. (2) Gas Modeling and Relaxation The gas molecules after energy minimization are placed into a periodic box to obtain a periodic gas model, and then the periodic gas model is subjected to energy minimization. The gas model after energy minimization is then subjected to molecular dynamics simulation of the NVT ensemble to obtain a relaxed gas model. (3) Leakage interface modeling and relaxation A vacuum layer and an isolation layer are constructed, and then the vacuum layer, the microcracked iron model, the relaxed gas model, and the isolation layer are sequentially spliced together. The atomic positions of the iron atoms are fixed to obtain a layered gas leakage interface model. The gas leakage interface model is subjected to energy minimization processing, and then molecular dynamics simulation of the NVT ensemble is performed to obtain the molecular dynamics trajectory file. (4) Analysis of simulation results Based on molecular dynamics trajectory files, the changes in gas molecule concentration distribution, radial distribution, and mean square displacement are analyzed. The leakage rate of gas in the microcrack is calculated using the formula qt = P1V - P2V, where q represents the leakage rate of gas in the microcrack, t represents the leakage time, V represents the gas volume, P1 represents the gas pressure before leakage, and P2 represents the gas pressure after leakage.
2. The molecular dynamics simulation method for gas leakage in metal microcracks as described in claim 1, characterized in that, In step (1), the bcc iron cell is: JCPDS No. 6-0696; the metal layer wall thickness of the hollow microchannel is...
3. The molecular dynamics simulation method for gas leakage in metal microcracks as described in claim 1, characterized in that, In step (2), the gas includes one or more of the following: helium, argon, neon, nitrogen, hydrogen, oxygen, carbon dioxide, carbon monoxide, water vapor, ammonia, methane, ethane, propane, butane, ethylene, propylene, and butene.
4. The molecular dynamics simulation method for gas leakage in metal microcracks as described in claim 1, characterized in that, In step (2), the a, b, α, β, and γ of the periodic gas model are consistent with the supercell iron model in step (1), and the c of the periodic gas model is determined by the gas pressure, which is 0.01-70 atm.
5. The molecular dynamics simulation method for gas leakage in metal microcracks as described in claim 1, characterized in that, In step (2), the molecular dynamics simulation force field includes one of the following: COMPASS force field, cvff force field, and pcff force field. The temperature is controlled by the Nosé-Hoover hot bath method, and the temperature, dynamic time, and time step are 73.15-673.15K, 2000-40000ps, and 0.5-2fs, respectively.
6. The molecular dynamics simulation method for gas leakage in metal microcracks as described in claim 1, characterized in that, In steps (2) and (3), the energy minimization process comprehensively utilizes the steepest descent method, the conjugate gradient method, and the Newton-Raphson iteration method. The force fields used include one of the COMPASS force field, the cvff force field, and the pcff force field. The convergence thresholds for the maximum energy change, the maximum force, and the maximum displacement are 2×10⁻⁶. -5 -0.001 kcal / mol 7. The molecular dynamics simulation method for gas leakage in metal microcracks as described in claim 1, characterized in that, In step (3), the isolation layer is a periodic supercell iron model constructed based on bcc iron unit cells. The thickness c of the isolation layer includes 1-9 layers of iron atoms, and the a, b, α, β, and γ of the isolation layer are consistent with the microcrack iron model. The vacuum layer does not contain gas molecules, and the a, b, α, β, and γ of the vacuum layer are consistent with the microcrack iron model. The thickness c of the vacuum layer is... vacuum For the thickness c of the periodic gas model gas 0.2-2 times.
8. The molecular dynamics simulation method for gas leakage in metal microcracks as described in claim 1, characterized in that, In step (3), the molecular dynamics simulation force field includes one of the following: COMPASS force field, cvff force field, and pcff force field. The temperature is controlled by the Nosé-Hoover hot bath method, and the simulation temperature, dynamic time, and time step are set to 73.15-673.15K, 100-3000ps, and 0.1-2fs, respectively.