A method for constructing a molecular dynamics model of monolayer molybdenum disulfide containing point defects

Abstract

The invention discloses a method for constructing a molecular dynamics model of monolayer molybdenum disulfide containing point defects. First, an atomic coordinate is obtained by constructing a molecular dynamics model of defect-free monolayer molybdenum disulfide through the open-source software LAMMPS. Secondly, the coordinate relationship between defective atoms is obtained by analyzing the atomic defect forms of six kinds of point-defect molybdenum disulfide, and a program for processing the atomic coordinates of six kinds of point-defect molybdenum disulfide is obtained through programming according to the coordinate relationship between atoms. Finally, the atomic coordinates of defect-free monolayer molybdenum disulfide are imported into the program for operation, and a molecular dynamics model of monolayer molybdenum disulfide with specific defects and specific defect concentrations is obtained, providing a reference for the modeling of point-defect molybdenum disulfide in the study of various properties of monolayer defective molybdenum disulfide at the nanoscale.

Description

Technical Field

[0001] The present invention belongs to the technical field of molecular dynamics, and particularly relates to a method for constructing a molecular dynamics model of monolayer molybdenum disulfide containing point defects. Background Art

[0002] Molybdenum disulfide (MoS2) has a unique "sandwich" structure, and the adjacent two molecular layers are connected by weak van der Waals forces. The distance between each layer is about 0.65 nm, which makes MoS2 widely studied as a solid lubricant and catalyst, and MoS2 solid lubricants have been widely used in the moving mechanisms of spacecraft. The molybdenum (Mo) atoms and sulfur (S) atoms in the MoS2 layer form S-Mo-S bonds in the form of covalent bonds, making MoS2 have strong intra-layer forces and showing a mechanical strength 30 times higher than that of steel; the semiconductor electrical properties of monolayer MoS2 are converted from indirect bandgap to direct bandgap, making it have great potential in integrated circuit applications.

[0003] In order to give full play to the advantages of MoS2, in principle, it is necessary to obtain large-area defect-free MoS2 thin films. Currently, the existing technologies for preparing MoS2 thin films mainly include mechanical exfoliation method, physical vapor deposition method, chemical vapor deposition method, solution chemical ultrasonic exfoliation method, and thermal decomposition method. However, the MoS2 thin films obtained by these preparation methods all have various defects more or less. The common types of point defects are divided into vacancy point defects and antisite defects. The main vacancy point defects are: single sulfur atom vacancy V S , paired sulfur atom vacancy V S2 , single molybdenum atom and surrounding three sulfur atom vacancy V MoS3 , single molybdenum atom and surrounding six sulfur atom vacancy V MoS6 . The main antisite defects are: single molybdenum atom replacing paired sulfur atom Mo S2 and paired sulfur atom replacing single molybdenum atom S2 Mo . The structural defects in MoS2 thin films will have a significant impact on its friction performance, electrical, optical, thermal, chemical, and mechanical properties, etc.

[0004] The common point defects of MoS2 are at the nanoscale. Due to the limitations of experimental equipment, it is still a great challenge to conduct experiments at the nanoscale. The molecular dynamics method is a widely used method for calculating complex systems at present, and it has the advantages of cost saving and good repeatability. Summary of the Invention

[0005] In order to overcome the deficiencies of the prior art, the present invention provides a method for constructing a molecular dynamics model of monolayer molybdenum disulfide with point defects. First, an undefected monolayer molybdenum disulfide molecular dynamics model is constructed by using the open-source software LAMMPS to obtain atomic coordinates. Secondly, the coordinate relationship between defective atoms is obtained by analyzing the atomic defect forms of six types of point-defect molybdenum disulfide, and programming is carried out based on the coordinate relationship between atoms to obtain a program for processing the atomic coordinates of six types of point-defect molybdenum disulfide. Finally, the atomic coordinates of the undefected monolayer molybdenum disulfide are imported into the program for operation to obtain a molecular dynamics model of monolayer molybdenum disulfide with specific defects and specific defect concentrations, providing a reference for the modeling of point-defect molybdenum disulfide in the study of various properties of monolayer defective molybdenum disulfide at the nanoscale.

[0006] The technical solution adopted by the present invention to solve its technical problems includes the following steps:

[0007] Step 1: According to the atomic arrangement characteristics of undefected monolayer MoS2, an undefected monolayer MoS2 primitive cell model is established. According to the periodicity of the crystal structure of monolayer MoS2, the primitive cell is expanded to establish an undefected monolayer MoS2 molecular dynamics model with the required size, and its atomic coordinates are exported. Specifically:

[0008] Monolayer MoS2 is a planar molecular model with a sandwich structure composed of S-Mo-S atoms. One layer of Mo atoms is located between two layers of S atoms. The S atoms and Mo atoms are each arranged symmetrically in a hexagonal shape. The distance between each S atom and 3 Mo atoms is equal, and each Mo atom is surrounded by 6 equidistant S atoms. The Mo atom layer and the S atom layer are bonded by covalent bonds, where the Mo-S bond length is 0.241 nm, and the bond angles of Mo-S-Mo and S-Mo-S are both 81.787°. The distance between the upper S atom and the lower S atom of monolayer MoS2 is 0.3241 nm.

[0009] According to the above structural characteristics of monolayer MoS2, the primitive cell coordinates are calculated, and the primitive cell parameters are entered in the open-source software LAMMPS to obtain the primitive cell model of MoS2 as an expandable unit. The primitive cell is expanded along the X and Y directions to obtain an undefected monolayer MoS2 molecular dynamics model with the required size and export the coordinates of each atom of the expanded undefected monolayer MoS2.

[0010] Step 2: According to the atomic deletion forms of four types of monolayer MoS2 with vacancy point defects and two types of monolayer MoS2 with antisite point defects, analyze the coordinate relationship between defective atoms, write an algorithm, and perform deletion and replacement operations on the atomic coordinates of undefected monolayer MoS2 to obtain a molecular dynamics model of monolayer MoS2 with vacancy and antisite point defects with the required defect concentration. Specifically:

[0011] Step 2-1: The atomic deletion forms of the four types of vacancy defects in MoS2 monolayer MoS2 are as follows:

[0012] (1) Monosulfur atom vacancy defect V S is the random deletion of sulfur atoms in the upper and lower sulfur atom layers of monolayer MoS2;

[0013] (2) Disulfur atom vacancy defect form V S2 is the random deletion of paired sulfur atoms with the same X and Y coordinates in the upper and lower sulfur atom layers of monolayer MoS2;

[0014] (3) Monomolybdenum atom and surrounding trisulfur atom vacancy defect V MoS3 is the random deletion of the molybdenum atom in monolayer MoS2 and three sulfur atoms in the same atomic layer that are adjacent to it and form bonds;

[0015] (4) Monomolybdenum atom and surrounding hexasulfur atom vacancy defect V MoS6 is the random deletion of the molybdenum atom in monolayer MoS2 and six upper and lower layer sulfur atoms that are adjacent to it and form bonds;

[0016] According to the atomic deletion characteristics of the above four types of vacancy defect monolayer MoS2, the atomic coordinate data obtained in Step 1 are processed to obtain a monolayer MoS2 model with the desired defect concentration; here, the defect concentration refers to the ratio of the number of missing atoms to the total number of atoms;

[0017] Step 2-2: The atomic substitution forms of the two types of antisite defects in monolayer MoS2 are as follows:

[0018] (1) Monomolybdenum atom replaces disulfur atom defect Mo S2 is to use 1 molybdenum atom to replace the sulfur atom pair with equal X and Y coordinates in the upper and lower sulfur atom layers, and this molybdenum atom is located in the molybdenum atom layer under the X and Y coordinates of the replaced sulfur atoms;

[0019] (2) Disulfur atom replaces monomolybdenum atom defect S2 Mo is to use a sulfur atom pair to replace the molybdenum atom, and this sulfur atom pair is located in the upper and lower sulfur atom layers under the X and Y coordinates of the replaced molybdenum atom;

[0020] According to the atomic substitution characteristics of the above two types of antisite defect monolayer MoS2, the atomic coordinate data obtained in Step 1 are processed to obtain an antisite defect monolayer MoS2 model with the desired defect concentration and its atomic coordinates; here, the defect concentration refers to the ratio of the number of replaced atoms to the total number of atoms.

[0021] The beneficial effects of the present invention are as follows:

[0022] 1. The present invention analyzes the coordinate relationships between atoms of various defect atoms in a monolayer MoS2 with 6 common point defects. Based on the atomic coordinates of a defect-free monolayer MoS2, all combinations of defect atoms are found by means of programming, and the combinations of defect atoms are randomly deleted or replaced according to a given defect concentration, thereby generating a molecular dynamics model of monolayer MoS2 with point defects.

[0023] 2. The method of the present invention is simple, fast, and easy to implement. It can construct molecular dynamics models of monolayer MoS2 with different defect concentrations and different types of point defects, and is applicable to molecular dynamics simulations of monolayer MoS2 with point defects. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] Figure 1 These are the three-view drawings of the primitive cell model of MoS2 of the present invention, where (a) is the front view, (b) is the left view, (c) is the top view, and (d) is the axonometric view.

[0025] Figure 2 These are the three-view drawings of the molecular dynamics model of monolayer MoS2 of the present invention, where (a) is the front view, (b) is the left view, (c) is the top view, and (d) is the axonometric view.

[0026] Figure 3 This is the interface of the atomic coordinate data processing program for monolayer MoS2 of the present invention.

[0027] Figure 4 These are the partial model diagrams of monolayer MoS2 with four types of vacancy point defects with a defect concentration of 1% of the present invention. (a) The atomic configuration of monolayer MoS2 with a defect concentration of 1% V S The atomic configuration of the defective monolayer MoS2, (b) the atomic configuration of the defective monolayer MoS2 with a defect concentration of 1% V S2 The atomic configuration of the defective monolayer MoS2, (c) the atomic configuration of the defective monolayer MoS2 with a defect concentration of 1% V MoS3 The atomic configuration of the defective monolayer MoS2, (d) the atomic configuration of the defective monolayer MoS2 with a defect concentration of 1% V MoS6 The atomic configuration of the defective monolayer MoS2.

[0028] Figure 5 These are the partial model diagrams of monolayer MoS2 with two types of antisite defects with a defect concentration of 1% of the present invention. (a) The atomic configuration of monolayer MoS2 with a defect concentration of 1% Mo S2 The atomic configuration of the defective monolayer MoS2, (b) the atomic configuration of the defective monolayer MoS2 with a defect concentration of 1% S2 Mo The atomic configuration of the defective monolayer MoS2. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0029] The present invention will be further described below in conjunction with the drawings and embodiments.

[0030] The purpose of the present invention is to construct a modeling method for common point defect monolayer MoS2 based on molecular dynamics, providing a reference for point defect MoS2 modeling in the performance of point defect monolayer MoS2 at the nanoscale.

[0031] A method for constructing a molecular dynamics model of monolayer molybdenum disulfide with point defects, comprising the following steps:

[0032] Step 1: According to the atomic arrangement characteristics of defect-free monolayer MoS2, establish a primitive cell model of defect-free monolayer MoS2. According to the periodicity of the crystal structure of monolayer MoS2, expand the primitive cell to establish a molecular dynamics model of defect-free monolayer MoS2 with the required size, and export its atomic coordinates.

[0033] Step 2: According to the atomic deletion forms of four common vacancy-site defect monolayer MoS2 and two common anti-site defect monolayer MoS2, analyze the coordinate relationship between defective atoms, write a specific algorithm, and perform deletion and replacement operations on the atomic coordinates of defect-free monolayer MoS2 to obtain a molecular dynamics model of monolayer MoS2 with vacancy and anti-site defects with the required defect concentration.

[0034] In Step 1, the specific method for constructing the primitive cell and molecular dynamics model of defect-free monolayer MoS2 is as follows:

[0035] Monolayer MoS2 is a planar molecular model with a sandwich structure composed of S-Mo-S atoms. One layer of Mo atoms is located between two layers of S atoms. The S atoms and Mo atoms are each arranged symmetrically in a hexagonal shape. The distance between each S atom and 3 Mo atoms is equal, and each Mo atom is surrounded by 6 equidistant S atoms. The Mo atom layer and the S atom layer are bonded by covalent bonds. Among them, the Mo-S bond length is about 0.241 nm, and the bond angles of Mo-S-Mo and S-Mo-S are both 81.787°. The distance between the upper S atom and the lower S atom in monolayer MoS2 is 0.3241 nm. According to the above structural characteristics of monolayer MoS2, calculate the primitive cell coordinates, enter the unit cell parameters in the open-source software LAMMPS, obtain the primitive cell model of MoS2 as an expandable unit, and expand the primitive cell along the X and Y directions to obtain a molecular dynamics model of defect-free monolayer MoS2 with the required size and export the coordinates of each atom of the expanded defect-free monolayer MoS2.

[0036] In Step 2: The atomic deletion forms of four common vacancy-site defects in MoS2 are as follows: (1) Single sulfur atom vacancy defect (V S ) is the random deletion of sulfur atoms in the upper and lower sulfur atom layers of monolayer MoS2; (2) Pair of sulfur atom vacancy defect form (V S2 ) is the random deletion of paired sulfur atoms (with the same X and Y coordinates) in the upper and lower sulfur atom layers of monolayer MoS2; (3) Single molybdenum atom and surrounding three sulfur atom vacancy defect (V MoS3 ) is the random deletion of a molybdenum atom in monolayer MoS2 and three sulfur atoms in the same atomic layer that are adjacent (bonded) to it; (4) Single molybdenum atom and surrounding six sulfur atom vacancy defect (V MoS6) is the random absence of molybdenum atoms in single-layer MoS2 and the six upper and lower adjacent (bonded) sulfur atoms. According to the atomic absence characteristics of the above four types of vacancy-site defect MoS2, a specific algorithm is written, an interface is designed, and the atomic coordinates obtained in Step 1 are imported into the program. By processing the atomic coordinate data through the program, a single-layer MoS2 model with vacancy-site defects of the required defect concentration (the ratio of the number of absent atoms to the total number of atoms) is obtained; the two forms of atomic substitution for anti-site defects are: (1) single molybdenum atom substitution for sulfur atom pair defect (Mo S2 ) is to use 1 molybdenum atom to replace the sulfur atom pair (X and Y coordinates are equal) in the upper and lower sulfur atom layers, and this molybdenum atom is located in the molybdenum atom layer under the X and Y coordinates of the replaced sulfur atom; (2) sulfur atom pair substitution for single molybdenum atom defect (S2 Mo ) is to replace the molybdenum atom with a sulfur atom pair, and this sulfur atom pair is located in the upper and lower sulfur atom layers under the X and Y coordinates of the replaced molybdenum atom. According to the atomic substitution characteristics of the above two types of anti-site defect MoS2, a specific algorithm is written, an interface is designed, and the atomic coordinates obtained in Step 1 are imported into the program. By processing the atomic coordinate data through the program, a single-layer MoS2 model with anti-site defects of the required defect concentration (the ratio of the number of replaced atoms to the total number of atoms) and its atomic coordinates are obtained. Specific embodiments:

[0038] 1. According to the model structure characteristics of single-layer MoS2, the lattice parameters of defect-free single-layer MoS2 are The primitive cell is composed of 2 middle-layer Mo atoms, 2 upper-layer S atoms and 2 lower-layer S atoms, and the coordinates (unit: angstrom ) are respectively: (0.91395, 0, 4.460154)×n, (3.65578, 1.583, 4.460154)×n, (0, 1.583, 2.903)×n, (2.74185, 0, 6.0904)×n, (0, 1.583, 2.903)×n and (2.74185, 0, 2.903)×n, where n is any non-zero constant, and n takes 1 in the embodiment. From the above information, the basis vectors of the unit cell are typed in the open-source software LAMMPS as a1 = (1, 0, 0), a2 = (0, 0.0577316, 0), a3 = (0, 0, 0.590992), and the six atomic positions in the space defined by the corresponding basis vectors are typed. The MoS2 primitive cell model is obtained as Figure 1 shown. Taking the above-obtained primitive cell as the smallest periodic repeating unit, it is replicated in the X direction and the Y direction and extended to a size of The total number of atoms is 693, and a large-area flaky single-layer MoS2 model is obtained as Figure 2As shown. Export the coordinates of each atom to a text file. From the total number of atoms, it can be seen that to achieve a defect concentration of 1%, the number of missing atoms and the number of replaced atoms need to be 7 or 8.

[0039] 2. One of the vacancy defects: Randomly delete the upper or lower layer S atoms until the number of missing atoms (7 in this example) is reached to obtain a single sulfur atom vacancy defect monolayer MoS2 model (V S ) with a defect concentration of 1%; Another vacancy defect: Screen the S atoms with equal X and Y coordinates and record the atom numbers in pairs. The coordinates of the deleted atoms are constrained as follows:

[0040] X S1 = X S2 , Y S1 = Y S2 (1)

[0041] Z S1 = 6.0904 or 2.903 (2)

[0042] Z S2 = 2.903 or 6.0904 (3)

[0043] Z S1 ≠ Z S2 (4)

[0044] Among them, X S1 , Y S1 , Z S1 are the X, Y, and Z coordinates of the first S atom respectively, and X S2 , Y S2 , Z S2 are the X, Y, and Z coordinates of the second S atom respectively. Randomly delete the recorded atom groups until the number of missing atoms reaches 8 to obtain a pair of sulfur atom vacancy defect monolayer MoS2 model (V S2 ) with a defect concentration of 1%; Another vacancy defect: Obtain the 3 S atoms in the same layer that bond with each Mo atom. The coordinate constraint relationship is as follows:

[0045] X S1 - X Mo <1.8261, Y S1 = Y Mo (5)

[0046] X Mo - X S2 <0.9161, X S2 = X S3 (6)

[0047] Y Mo - Y S2 = Y S3-Y Mo <1.584 (7)

[0048] Z S1 =Z S2 =Z S3 =6.0904 or 2.903 (8)

[0049] Wherein, X S1 、Y S1 、Z S1 are the X, Y, and Z coordinates of the first S atom respectively, X S2 、Y S2 、Z S2 are the X, Y, and Z coordinates of the second S atom respectively, X S3 、Y S3 、Z S3 are the X, Y, and Z coordinates of the third S atom respectively, X Mo 、Y Mo are the X and Y coordinates of a random Mo atom respectively. Record the atomic numbers in groups of every four atoms that satisfy the coordinate relationship, and randomly delete the recorded atomic groups until the number of missing atoms reaches 8, then a monolayer molybdenum disulfide model with a single molybdenum atom and peripheral trisulfur atom vacancy defects with a defect concentration of 1% can be obtained (V MoS3 ); Vacancy defect four: Obtain the 6 S atoms bonded to each Mo atom, and the coordinate constraint relationship is increased on the basis of formulas (5)-(8):

[0050] X S4 -X Mo <1.8261, Y S4 =Y Mo (9)

[0051] X Mo -X S5 <0.9161, X S5 =X S6 (10)

[0052] Y Mo -Y S5 =Y S6 -Y Mo <1.584 (11)

[0053] Z S4 =Z S5 =Z S6 =2.903 or 6.0904 (12)

[0054] Z S4 =Z S5 =Z S6 ≠Z S1 =Z S2 =ZS3 (13)

[0055] Among them, X S4 , Y S4 , Z S4 are the X, Y, and Z coordinates of the fourth S atom respectively, and X S5 , Y S5 , Z S5 are the X, Y, and Z coordinates of the fifth S atom respectively, and X S6 , Y S6 , Z S6 are the X, Y, and Z coordinates of the sixth S atom respectively, and X Mo , Y Mo are the X and Y coordinates of a random Mo atom respectively. Record the atomic numbers in groups of seven atoms that satisfy the coordinate relationship, and randomly delete the recorded atomic groups until the number of missing atoms reaches 7 (i.e., randomly delete any atomic group), then a single-molybdenum-atom and surrounding six-sulfur-atom vacancy defect monolayer MoS2 model with a defect concentration of 1% (V MoS6 ) can be obtained; write a specific algorithm according to the coordinate relationship of the defect atoms of the above four types of vacancy point defects, design a program interface, and implement the function of deleting atoms. Import the atomic coordinates obtained in the first step into the program, select the corresponding point defect type and defect concentration (1% in this example) for data processing, export the processed data to obtain the atomic coordinates of the corresponding vacancy defect, and the vacancy point defect model under this atomic coordinate is as shown in Figure 4 . One of the anti-site defects: Screen S atoms with equal X and Y coordinates and record the atomic serial numbers in pairs to form S atom pairs, randomly replace 7 S atom pairs with Mo atoms, then a monolayer MoS2 model with a single-molybdenum-atom replacing pair of sulfur atoms defect with a defect concentration of 1% (Mo S2 ) can be obtained. The coordinate constraint relationship of 3 atoms is:

[0056] X Mo = X S1 = X S2 , Y Mo = Y S1 = Y S2 (14)

[0057] Z Mo = 4.460154 (15)

[0058] Z S1 = 6.0904 or 2.903 (16)

[0059] Z S2 = 2.903 or 6.0904 (17)

[0060] Z S1 ≠ Z S2 (18)

[0061] Among them, X S1 , Y S1 , Z S1 are the X, Y, and Z coordinates of the first S atom in the replaced S atom pair, respectively. X S2 , Y S2 , Z S2 are the X, Y, and Z coordinates of the second S atom in the replaced S atom pair, respectively. X Mo , Y Mo , Z Mo are the X, Y, and Z coordinates of the Mo atom to be added, respectively. The second type of antisite defect: Obtain and record the X and Y coordinates of each Mo atom, randomly replace 7 Mo atoms with S atom pairs, and a monolayer MoS2 model with a defect concentration of 1% of single Mo atom defects replaced by S atoms (S2 Mo ) can be obtained. Its coordinate constraint relationship is:

[0062] X S1 = X S2 = X Mo , Y S1 = Y S2 = Y Mo (19)

[0063] Z S1 = 6.0904 or 2.903 (20)

[0064] Z S2 = 2.903 or 6.0904 (21)

[0065] Z S1 ≠ Z S2 (22)

[0066] Among them, X S1 , Y S1 , Z S1 are the X, Y, and Z coordinates of the first S atom in the S atom pair to be added, respectively. X S2 , Y S2 , Z S2 are the X, Y, and Z coordinates of the second S atom in the S atom pair to be added, respectively. X Mo , Y Mo are the X and Y coordinates of the replaced Mo atom, respectively. Therefore, import the atomic coordinates obtained in the first step into the program for data processing, and export the processed data to obtain the corresponding monolayer MoS2 model with antisite defects as shown in Figure 5 as follows.

Claims

1. A method for constructing a molecular dynamics model of monolayer molybdenum disulfide with point defects, characterized in that, It includes the following steps: Step 1: According to the atomic arrangement characteristics of defect-free monolayer MoS2, establish a primitive cell model of defect-free monolayer MoS2. According to the periodicity of the crystal structure of monolayer MoS2, expand the primitive cell to establish a molecular dynamics model of defect-free monolayer MoS2 with the required size, and export its atomic coordinates. Specifically: Monolayer MoS2 is a planar molecular model with a sandwich structure composed of S-Mo-S atoms. One layer of Mo atoms is located between two layers of S atoms. S atoms and Mo atoms are each arranged symmetrically in a hexagonal pattern. The distance between each S atom and 3 Mo atoms is equal, and each Mo atom is surrounded by 6 equidistant S atoms. The Mo atom layer and the S atom layer are bonded by covalent bonds. Among them, the Mo-S bond length is 0.241 nm, and the bond angles of Mo-S-Mo and S-Mo-S are both 81.787°. The distance between the upper S atom and the lower S atom in monolayer MoS2 is 0.3241 nm. According to the above structural characteristics of monolayer MoS2, calculate the primitive cell coordinates, enter the unit cell parameters in the open-source software LAMMPS to obtain the primitive cell model of MoS2 as an expandable unit, expand the primitive cell in the X and Y directions to obtain a molecular dynamics model of defect-free monolayer MoS2 with the required size, and export the coordinates of each atom of the expanded defect-free monolayer MoS2. Step 2: According to the atomic deletion forms of four types of vacancy-site defect monolayer MoS2 and two types of anti-site defect monolayer MoS2, analyze the coordinate relationship between defect atoms, write an algorithm, and perform deletion and replacement operations on the atomic coordinates of defect-free monolayer MoS2 to obtain molecular dynamics models of vacancy and anti-site defect monolayer MoS2 with the required defect concentrations. Specifically: Step 2-1: The atomic deletion forms of four types of vacancy-site defect monolayer MoS2 in MoS2 are: (1) Single sulfur atom vacancy defect V S is the random absence of sulfur atoms in the upper and lower sulfur atom layers of monolayer MoS2; (2) For the form of sulfur atom vacancy defect V S2 It is the random loss of paired sulfur atoms with the same X and Y coordinates in the upper and lower sulfur atom layers of monolayer MoS2; (3) Single molybdenum atom and the surrounding three sulfur atom vacancy defect V MoS3 It is the random absence of the molybdenum atom in monolayer MoS2 and three sulfur atoms in the same atomic layer that are adjacent to and bonded to it. (4) Single molybdenum atom and surrounding six sulfur atom vacancy defect V MoS6 It is the random absence of the molybdenum atom in monolayer MoS2 and the six upper and lower layer sulfur atoms that are bonded to it in close proximity; Process the atomic coordinate data obtained in Step 1 according to the above atomic deletion characteristics of four types of vacancy-site defect monolayer MoS2 to obtain a vacancy-site defect monolayer MoS2 model with the required defect concentration. Here, the defect concentration refers to the ratio of the number of missing atoms to the total number of atoms. Step 2-2: The atomic replacement forms of two types of anti-site defect monolayer MoS2 are: (1)Single molybdenum atom substitution for sulfur atom defect Mo S2 One molybdenum atom is used to replace the sulfur atom pair with equal X and Y coordinates in the upper and lower sulfur atom layers, and the molybdenum atom is located in the molybdenum atom layer under the X and Y coordinates of the replaced sulfur atom; (2) Replace the single molybdenum atom defect S2 with a sulfur atom pair Mo To replace the molybdenum atom with a sulfur atom pair, the sulfur atom pair is located in the upper and lower sulfur atom layers under the X and Y coordinates of the replaced molybdenum atom; Process the atomic coordinate data obtained in Step 1 according to the above atomic replacement characteristics of two types of anti-site defect monolayer MoS2 to obtain an anti-site defect monolayer MoS2 model with the required defect concentration and its atomic coordinates. Here, the defect concentration refers to the ratio of the number of replaced atoms to the total number of atoms.

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