Intragranular magnetic field construction method for complex atom defect

Abstract

The invention relates to an intragranular magnetic field construction method for complex atom defects, and belongs to the field of quantum information science. Comprising the following steps: constructing initial unit cells and expanding the initial unit cells into super unit cells; carrying out natural isotope substitution in the superunit cells; carrying out stacking fault on the super unit cells and removing corresponding atom introduction defects; based on a first principle, performing structure optimization on the super-unit cell with the introduced defect until the super-unit cell with the optimized structure has a stable configuration, and obtaining the super-unit cell with the optimized structure; performing static electronic structure calculation to obtain magnetization density distribution data of the supercell after structure optimization; performing calculation according to the magnetization density distribution data to obtain spin magnetic moment distribution of the supercell after structure optimization; and according to the spin magnetic moment distribution, calculating the magnetic field induction intensity of any point in the supercell after structure optimization, and carrying out magnetic field construction. According to the method, an intragranular magnetic field is constructed, so that a basis is provided for researching the spin coherence property of a color center material with complex atom defects.

Description

Technical Field

[0001] The present invention relates to the field of quantum information science, and in particular to a method for constructing an intracrystalline magnetic field of a complex atomic defect. Background Art

[0002] Solid-state spin systems, with their advantages of long coherence time, high stability, and high integration density, have attracted widespread attention in technologies such as quantum computing and quantum precision measurement. Silicon carbide (SiC) color centers are a type of quantum material for solid-state spin systems. Recent research has discovered a high-performance color center within SiC stacking faults at room temperature. Its uniform dephasing time at room temperature reaches 40.6 μs, and its inhomogeneous dephasing time (T2*) is 1.2 μs, surpassing the T2* limit of 1 μs for other SiC color centers at room temperature. Stacking faults arise when the stacking order of a crystal is disrupted, and multiple stacking order disruptions can occur within a relatively small number of crystal layers. Stacking faults have numerous configurations, and these surface defects increase the complexity of the intracrystalline magnetic field effects on spins. These defects may harbor a large number of undiscovered high-performance color centers, leading to the unresolved coherence time limits of SiC color centers and other solid-state spin systems.

[0003] Cluster correlation expansion (CCE) theory is commonly used to study the coherence properties of solid-state spin systems. However, the configurations of color center materials studied currently generally do not take into account complex atomic defects, resulting in existing CCE algorithms failing to consider the effects of intracrystalline magnetic fields on spin coherence.

[0004] Therefore, constructing an intracrystalline magnetic field to study the spin coherence properties of materials with complex atomic defect color centers is of great significance for exploring quantum materials with long coherence times. Quantum materials with long coherence times can improve the sensitivity of quantum precision detection and have broad application prospects in quantum computing and quantum communication. Summary of the Invention

[0005] In view of the above analysis, the present invention aims to provide a method for constructing the intracrystalline magnetic field of complex atomic defects to address the problem that the configuration of color center materials currently studied generally does not take complex atomic defects into account, resulting in low simulation accuracy due to the lack of consideration of the influence of complex atomic defects and the intracrystalline magnetic field on spin coherence. The present invention provides a method for constructing the intracrystalline magnetic field of complex atomic defects, which includes the following steps:

[0006] Determining the atomic type of the crystal, constructing an initial unit cell based on the atomic type and expanding it into a supercell; performing natural isotope substitution in the supercell; performing stacking faults on the supercell and removing corresponding atomic defects;

[0007] Based on first principles, the structure of the supercell with defects is optimized until the structurally optimized supercell has a stable configuration, thereby obtaining a structurally optimized supercell;

[0008] Through static electronic structure calculation, the magnetization density distribution data of the supercell after structural optimization is obtained;

[0009] Calculating the spin magnetic moment distribution of the structurally optimized supercell according to the magnetization density distribution data;

[0010] According to the spin magnetic moment distribution, the magnetic field induction intensity at any point in the supercell after structural optimization is calculated to construct the magnetic field.

[0011] Furthermore, performing stacking faults on the supercell and removing corresponding atomically introduced defects comprises:

[0012] S11, selecting a first position for a stacking fault in the supercell, and translating atomic coordinates at the first position to obtain a stacking fault;

[0013] S12. Select a second location for atomic removal in the supercell after the stacking fault, and remove corresponding atoms at the second location to introduce defects.

[0014] Furthermore, the structural optimization of the defect-introduced supercell based on first principles until the structurally optimized supercell has a stable configuration includes:

[0015] S21, setting optimization parameters;

[0016] S22, performing structural optimization on the supercell with defects introduced using first-principles calculation software according to the optimization parameters;

[0017] S23, judging whether the structurally optimized supercell has a stable configuration, if so, obtaining the structurally optimized supercell; otherwise, returning to step S12 to change the second position, and executing steps S22 and S23.

[0018] Furthermore, the optimization parameters include a limited number of electron steps, a limited number of ion steps, an ion step convergence accuracy, and an electron step convergence accuracy.

[0019] Furthermore, whether the supercell after structural optimization has a stable configuration is determined by judging whether the absolute value of the energy difference corresponding to adjacent ion steps is less than the ion step convergence accuracy.

[0020] Furthermore, the magnetization density distribution data of the structurally optimized supercell obtained by static electronic structure calculation includes:

[0021] Step S31: Keep the k-point setting and convergence accuracy unchanged, and set the spin-orbit coupling parameters;

[0022] Step S32: setting the number of ion steps to 0, using first-principles calculation software based on spin-orbit coupling parameters, obtaining the energy corresponding to the supercell through electron steps; iterating the electron steps until the electronic structure of the supercell converges;

[0023] Step S33: outputting the magnetization density distribution data corresponding to the electronic structure convergence of the supercell.

[0024] Furthermore, the energy corresponding to the current electron step is compared with the energy corresponding to the electron step of the previous iteration. If the absolute value of the difference between the two is less than the electron step convergence accuracy, it is determined that the electronic structure of the supercell is converged.

[0025] Furthermore, the spin magnetic moment distribution of the supercell after structural optimization is calculated by the following formula:

[0026]

[0027] Among them, g e is the electron g factor, which is approximately 2.002319; μ B is the Bohr magneton; m is the magnetization density distribution; V FFT is the total number of FFT grids; is the spin angular momentum vector.

[0028] Furthermore, the magnetic field induction intensity at any point in the supercell after structural optimization is calculated using the following formula:

[0029]

[0030] Where μ0 is the vacuum permeability, is the spin magnetic moment distribution, is the vector from the spin magnetic moment to any point in the supercell, and r is the distance from the spin magnetic moment to any point in the supercell.

[0031] Furthermore, constructing an initial unit cell based on the atomic type and expanding it into a supercell includes:

[0032] Setting crystal lattice parameters and atomic coordinates based on the atomic type, and constructing an initial unit cell according to the crystal lattice parameters and atomic coordinates;

[0033] The initial unit cell is repeatedly expanded to obtain a supercell.

[0034] Compared with the prior art, the present invention can achieve at least one of the following beneficial effects:

[0035] 1. The present invention introduces defects by performing stacking faults on the supercell and removing the corresponding atoms, taking into account the complexity of the influence of the intracrystalline magnetic field on the spin, and provides a basis for improving the accuracy of the calculation results of the intracrystalline magnetic field.

[0036] 2. The present invention provides a basis for improving the accuracy of simulating the spin coherence properties of materials with complex atomic defect color centers by constructing an intracrystalline magnetic field.

[0037] 3. The present invention screens the spin magnetic moment based on the preset boundary of the supercell. When calculating the magnetic field induction intensity at any point in the supercell, the spin magnetic moment of electrons closer to the point is screened for calculation. While meeting the calculation accuracy, the calculation time is greatly reduced and the efficiency is improved.

[0038] 4. The present invention performs virtual cell mapping according to the coordinates of the calculation boundary. When the calculation point is close to the edge of the supercell, the area beyond the supercell range in the hexahedron region is mapped to the corresponding area of ​​the supercell, thereby improving the accuracy of the calculation results of the intracrystalline magnetic field.

[0039] In the present invention, the above-mentioned technical solutions can be combined with each other to achieve more preferred combinations. Other features and advantages of the present invention will be described in the following description, and some advantages will become apparent from the description or be learned through practice of the present invention. The objectives and other advantages of the present invention can be realized and obtained through the contents particularly pointed out in the description and drawings. BRIEF DESCRIPTION OF THE DRAWINGS

[0040] The accompanying drawings are only for the purpose of illustrating particular embodiments and are not to be considered limiting of the present invention. Like reference symbols denote like parts throughout the drawings.

[0041] Figure 1 A flow chart of a method for constructing an intracrystalline magnetic field of a complex atomic defect provided by an embodiment of the present invention;

[0042] Figure 2 A schematic diagram of a silicon carbide stacking fault color center configuration used in simulations of an embodiment of the present invention;

[0043] Figure 3 Schematic diagram of the calculation boundary and calculation area of ​​a supercell according to an embodiment of the present invention;

[0044] Figure 4 Schematic diagram of the convergence of the magnetic field in a supercell calculated based on the spin magnetic moment in the calculation area of ​​the supercell according to an embodiment of the present invention. DETAILED DESCRIPTION

[0045] The preferred embodiments of the present invention will be described in detail below in conjunction with the accompanying drawings, wherein the accompanying drawings constitute a part of this application and are used together with the embodiments of the present invention to illustrate the principles of the present invention, and are not used to limit the scope of the present invention.

[0046] A specific embodiment of the present invention discloses a method for constructing an intracrystalline magnetic field of a complex atomic defect. Figure 1 As shown, the method includes the following steps:

[0047] Step S1, determining the atomic type of the crystal, constructing an initial unit cell based on the atomic type and expanding it into a supercell; performing natural isotope substitution in the supercell; performing stacking faults on the supercell and removing corresponding atoms to introduce defects;

[0048] Step S2, performing structural optimization on the supercell with defects based on first principles until the structurally optimized supercell has a stable configuration, thereby obtaining a structurally optimized supercell;

[0049] Step S3, obtaining magnetization density distribution data of the supercell after structural optimization through static electronic structure calculation;

[0050] Step S4, calculating the spin magnetic moment distribution of the supercell after structural optimization according to the magnetization density distribution data;

[0051] Step S5: Calculate the magnetic field induction intensity at any point in the supercell after structural optimization based on the spin magnetic moment distribution, and construct the magnetic field.

[0052] Specifically, in step S1, constructing an initial unit cell based on the atomic type and expanding it into a supercell includes:

[0053] Setting crystal lattice parameters and atomic coordinates based on the atomic type, and constructing an initial unit cell according to the crystal lattice parameters and atomic coordinates;

[0054] The initial unit cell is repeatedly expanded to obtain a supercell.

[0055] It should be noted that the crystal lattice parameters include the basis vectors of the unit cell and the angles between the crystal axes, which are used to describe the size and shape of a single unit cell; the basis vectors of the unit cell are the basic vectors that describe the crystal structure, usually expressed as three vectors They form the edges of the unit cell. Atomic coordinates are used to determine the positions of individual atoms within the unit cell. In simulation software, the size and shape of the initial unit cell are determined in three-dimensional space based on the set lattice parameters. Based on the atomic coordinates, the atoms are placed at corresponding positions within the initial unit cell to create the initial unit cell model. This initial unit cell is then repeatedly expanded to create a supercell model.

[0056] For example, assuming the crystal is cubic, use the variable The variables α, β, and γ represent the angles between the crystal axes b and c, a and c, and a and b, respectively. The angle between the crystal axes is set to α = β = γ = 90°. The atomic coordinates are expressed as fractional coordinates. Assuming that the fractional coordinates of an atom are (0.25, 0.25, 0.25), it means that the atom is located at a quarter position in all three coordinate axes of the unit cell.

[0057] Preferably, VESTA software is used for initial unit cell and supercell modeling.

[0058] Furthermore, performing natural isotope replacement in the supercell comprises:

[0059] determining naturally occurring isotopes of said atomic type and their concentrations;

[0060] Calculate the amount of isotopes of each type of atom based on the naturally occurring isotopes of the atom type and their concentrations;

[0061] The same number of corresponding atoms is randomly replaced in the supercell according to the isotope number of each type of atoms.

[0062] Specifically, the natural isotopes and concentrations of each atomic type are determined. For each atomic type, i.e., each class of atoms, the number of natural isotopes of each class of atoms is calculated by multiplying the number of atoms of that class in the supercell by the concentration of its natural isotope. Based on the number of natural isotopes of each class of atoms, the same number of atoms of that class in the supercell are randomly replaced with their natural isotopes.

[0063] For example, using VESTA simulation software, assuming that the crystal is silicon carbide 4H-SiC, its atomic types include carbon atoms C12 and silicon atoms Si28, and the crystal type is hexagonal. Set the basis vector of the initial unit cell to The angles between the crystal axes are set to α = β = 90°, γ = 120°, and the initial unit cell is Repeat the expansion in the direction 5, 5, and 5 times, respectively, to obtain a supercell; in which each carbon atom C12 and each silicon atom Si28 has its own number. The natural isotope of carbon atom C12 is determined to be C13, with a concentration of 1.1 at.%, and the natural isotope of silicon atom Si28 is determined to be Si29, with a concentration of 4.67 at.%. Assuming that the number of C12 and Si28 in the supercell is both 500, using 500*1.1 at.%, the number of C13 is approximately 6, and using 500*4.67 at.%, the number of Si29 is 23. Based on the number of C13, 6, Python is used to generate a first random number sequence with 6 elements, where each element has a value between 1 and 500 and each element has a different value. The value of the element represents the number of the carbon atom. In the supercell, replace the C12 with C13 for each element with the same number in the first random number sequence. Similarly, a second random number sequence with 23 elements is generated according to the number of Si29, 23, where the value range of each element is between 1 and 500 and the value of each element is different. In the supercell, Si28 with the same number corresponding to each element in the second random number sequence is replaced by Si29.

[0064] It should be noted that the unit at.% stands for atomic percentage, which represents the percentage of the number of atoms of this isotope to the total number of atoms of this type.

[0065] Furthermore, performing stacking faults on the supercell and removing corresponding atomically introduced defects comprises:

[0066] S11, selecting a first position for a stacking fault in the supercell, and translating atomic coordinates at the first position to obtain a stacking fault;

[0067] S12. Select a second location for atomic removal in the supercell after the stacking fault, and remove corresponding atoms at the second location to introduce defects.

[0068] For example, the silicon carbide stacking fault color center configuration used in the simulation of the embodiment of the present invention is as follows: Figure 2 As shown, in the supercell, the z coordinate (i.e., c coordinate) is greater than and less than The region where all atoms are located is taken as the first location for stacking fault. At this first location, the x coordinates (i.e., a coordinates) of all atoms are reduced by That is, translate to the left along the x-axis Then add the y coordinates (i.e. b coordinates) of all atoms That is, translate upward along the y-axis A stacking fault structure is obtained. In the supercell after the stacking fault, two locations with atomic coordinates of (3.08000, 7.11296, 13.21293) and (3.08000, 7.11296, 15.10500) in the absolute coordinate system are selected as the second locations for atomic removal. The corresponding atoms are removed at these second locations to form divacancy color centers, thereby introducing defects.

[0069] It can be understood that the present invention introduces defects by performing stacking faults on the supercell and removing corresponding atoms, taking into account the complexity of the influence of the intracrystalline magnetic field on the spin, and providing a basis for improving the accuracy of the calculation results of the intracrystalline magnetic field.

[0070] Specifically, in step S2, the structural optimization of the supercell with defects introduced based on first principles until the structurally optimized supercell has a stable configuration includes:

[0071] S21, setting optimization parameters;

[0072] S22, performing structural optimization on the supercell with defects introduced using first-principles calculation software according to the optimization parameters;

[0073] S23, judging whether the structurally optimized supercell has a stable configuration, if so, obtaining the structurally optimized supercell; otherwise, returning to step S12 to change the second position, and executing steps S22 and S23.

[0074] Preferably, the optimization parameters include the limited number of electron steps, the limited number of ion steps, the convergence accuracy of ion steps, and the convergence accuracy of electron steps.

[0075] It should be noted that, through the structural optimization, the position of atoms in space is adjusted, the atomic position distortion in the supercell is eliminated, and the total energy of the supercell is minimized, thereby obtaining a stable configuration. The electron density distribution and energy of the supercell are solved by the electron step. In each electron step, the wave function and energy of the electron are calculated according to the current position of the atomic nucleus. The movement of the atomic nucleus in the average potential field generated by the electron is obtained by the ion step. In each ion step, the force it receives is calculated according to the electronic structure at the current position of the atomic nucleus to update the speed of the atom, and the new position of the atom is calculated according to the speed of the updated atom. Therefore, it is necessary to set the maximum and minimum number of electron steps and ion steps. The ion step convergence accuracy and the electron step convergence accuracy refer to the criteria for judging whether the calculation results meet the convergence in the process of structural optimization. When the change in certain key calculation results (such as energy change, atomic displacement) is less than the corresponding convergence accuracy set, it is considered that the calculation results have converged.

[0076] Preferably, VASP software is used as the first-principles calculation software, and a corresponding input file is generated according to the optimization parameters, and the structure of the supercell with introduced defects is optimized through the input file.

[0077] Specifically, the input files include an INCAR file, a KPOINTS file, a POSCAR file, and a POTCAR file. The constructed defect-introduced supercell is exported to generate a first POSCAR file. The convergence accuracy is set to use a PBE pseudopotential, and the optimization parameters are written into the first INCAR file. A KPOINTS file containing k-points or only gamma points and a POTCAR pseudopotential file are generated. The defect-introduced supercell is structurally optimized using VASP software using these input files to generate a second POSCAR file.

[0078] It should be noted that the Brillouin zone refers to a periodically arranged region in reciprocal space. The Gamma point is the center of the Brillouin zone, and the k-point is the sampling point of the Brillouin zone. For crystal cells with high symmetry and relatively simple electronic structures, using only the Gamma point for relevant calculations can yield results that meet the required accuracy, greatly reducing the amount of computation and improving efficiency.

[0079] Preferably, whether the supercell after structural optimization has a stable configuration is determined by judging whether the absolute value of the energy difference between adjacent ion steps is less than the ion step convergence accuracy.

[0080] Specifically, in step S3, the magnetization density distribution data of the supercell after structural optimization is obtained by static electronic structure calculation includes:

[0081] Step S31: Keep the k-point setting and convergence accuracy unchanged, and set the spin-orbit coupling parameters;

[0082] Step S32: setting the number of ion steps to 0, using first-principles calculation software based on spin-orbit coupling parameters, obtaining the energy corresponding to the supercell through electron steps; iterating the electron steps until the electronic structure of the supercell converges;

[0083] Step S33: outputting the magnetization density distribution data corresponding to the electronic structure convergence of the supercell.

[0084] Preferably, the spin-orbit coupling parameters include: LSORBIT=TRUE, LNONCOLLINEAR=TRUE, LORBMOM=TRUE, GGA_COMPAT=FALSE.

[0085] It should be noted that, in the electronic step, the electronic wave function and energy corresponding to the supercell are obtained by constructing an effective potential and solving the Kohn-Sham equation.

[0086] Specifically, the energy corresponding to the current electron step is compared with the energy corresponding to the electron step of the previous iteration. If the absolute value of the difference between the two is less than the electron step convergence accuracy, it is determined that the electronic structure of the supercell is converged.

[0087] It should be noted that the total energy corresponding to the electronic structure of the supercell is converged to a minimum value through iterative electronic steps.

[0088] For example, VASP software is used as the first-principles calculation software. The spin-orbit coupling parameters are written into the first INCAR file to obtain a second INCAR file. Static calculations are performed based on the second INCAR file, the second POSCAR file, the KPOINTS file, and the POTCAR file to obtain the CHGCAR file and WAVECAR file corresponding to the convergence of the electronic structure of the supercell. The WAVECAR file contains the electron wave function data corresponding to the supercell, and the CHGCAR file contains the charge density distribution data and magnetization density distribution data corresponding to the supercell.

[0089] Specifically, in step S4, the spin magnetic moment distribution of the supercell after structural optimization is calculated using the following formula:

[0090]

[0091] Among them, g e is the electron g factor, which is approximately 2.002319; μ B is the Bohr magneton; m is the magnetization density distribution; V FFT is the total number of FFT grids; is the spin angular momentum vector.

[0092] Preferably, the direction of the spin angular momentum vector relative to the Cartesian coordinate system is (0, 0, 1).

[0093] It should be noted that the FFT grid refers to the grid used to discretize the real space or reciprocal space during the Fast Fourier Transform (FFT). Data reconstruction is performed on the real space or reciprocal space FFT grid based on the magnetization density distribution data, and the magnetization density distribution data on the FFT grid is converted into the spin magnetic moment distribution on the FFT grid according to formula (1). The spin magnetic moment distribution on the FFT grid means that each FFT grid point has a spin magnetic moment value.

[0094] Specifically, in step S5, the magnetic field induction intensity at any point in the supercell after structural optimization is calculated using the following formula:

[0095]

[0096] Where μ0 is the vacuum permeability, is the spin magnetic moment distribution, is the vector from the spin magnetic moment to any point in the supercell, and r is the distance from the spin magnetic moment to any point in the supercell.

[0097] Preferably, the magnetic field induction intensity at any point in the supercell is the sum of the magnetic field induction intensities generated by the screened spin magnetic moments at that point.

[0098] Preferably, a preset boundary of the supercell is set, and the spin magnetic moment is screened based on the spin magnetic moment distribution and the preset boundary of the supercell; the preset boundary of the supercell is a limiting length proportional to the lattice constant of the supercell.

[0099] Preferably, the schematic diagram of the calculation boundary and calculation area of ​​the supercell of the embodiment of the present invention is as follows: Figure 3 As shown in the figure, the solid line is the supercell boundary and the dotted line is the virtual cell. The method of screening the spin magnetic moment based on the preset boundary of the supercell includes:

[0100] Obtaining a calculation boundary based on the calculation point and the preset boundary of the supercell; the calculation boundary includes: a_min, a_max, b_min, b_max, c_min, c_max;

[0101] Performing virtual cell mapping according to the coordinates of the calculation boundary to obtain a calculation region;

[0102] According to the spin magnetic moment distribution, the corresponding spin magnetic moment in the calculation area is screened.

[0103] Specifically, performing virtual cell mapping according to the coordinates of the calculation boundary to obtain the calculation area includes:

[0104] Expanding the supercell with virtual cells according to the coordinates of the calculation boundary;

[0105] Within the scope of the virtual unit cell and supercell after cell expansion, a hexahedral region with the same angle as the basis vector is enclosed by the calculation boundary;

[0106] Mapping the area of ​​the hexahedral region that exceeds the supercell range to the corresponding area of ​​the supercell to obtain a first calculation area;

[0107] The area of ​​the hexahedral region that does not exceed the supercell range is used as the second calculation area;

[0108] The union of the first calculation area and the second calculation area is used as the calculation area.

[0109] For example, assuming that the area beyond the supercell in the hexahedral area falls on the lower left part of a virtual cell, the lower left part of the virtual cell is mapped to the corresponding area of ​​the supercell, that is, the lower left part of the supercell.

[0110] It should be noted that the calculation point refers to any point in the supercell where the magnetic field induction intensity is to be calculated. a_min and a_max are the minimum and maximum values ​​corresponding to the coordinates of the calculation point on the a-axis as the center and the preset boundary as the length in the a-axis direction; b_min and b_max are the minimum and maximum values ​​corresponding to the coordinates of the calculation point on the b-axis as the center and the preset boundary as the length in the b-axis direction; c_min and c_max are the minimum and maximum values ​​corresponding to the coordinates of the calculation point on the c-axis as the center and the preset boundary as the length in the c-axis direction. a_min should be less than the length of the lattice vector a, b_min should be less than the length of the lattice vector b, and c_min should be less than the length of the lattice vector c; a_max, b_max, and c_max should be greater than 0 and greater than a_min, b_min, and c_min, respectively. Formula (2) is used to obtain the magnetic field induction intensity generated by the magnetic moment at the center point on all FFT grid points in the calculation area.

[0111] Preferably, a_min, a_max, b_min, b_max, c_min, and c_max are coordinates of a coordinate system with lattice vectors as coordinate axes. When a_min>0, a_max<|a|, b_min>0, b_max<|b|, c_min>0, and c_max<|c|, virtual cell mapping is not required.

[0112] It can be understood that the present invention screens the spin magnetic moment based on the preset boundary of the supercell. When calculating the magnetic field induction intensity at any point in the supercell, the spin magnetic moment of the electrons closer to the point is screened for calculation. While meeting the calculation accuracy, the calculation time is greatly reduced and the efficiency is improved. The present invention performs virtual cell mapping based on the coordinates of the calculation boundary. When the calculation point is close to the edge of the supercell, the area in the hexahedron area that exceeds the supercell range is mapped to the corresponding area of ​​the supercell, thereby improving the accuracy of the calculation results of the magnetic field within the crystal.

[0113] For example, the embodiment of the present invention calculates the convergence of the magnetic field in the supercell based on the spin magnetic moment in the calculation area of ​​the supercell, such as Figure 4 As shown in the figure, the limit distance is the distance from the center point to all calculation boundaries, and the coordinates of the center point are (3.08000, 7.11296, 13.21293). From formula (2), we can see that the farther the magnetic moment is from the center point, the smaller its contribution to the magnetic field induction intensity at the center point. Figure 4It can be seen that as the restriction distance increases, that is, the calculation range increases, the calculation results of the magnetic field induction intensity at the center point converge, indicating that the correct magnetic field calculation results can be obtained by the above-mentioned method of screening the spin magnetic moment based on the preset boundary of the supercell.

[0114] It can be understood that the present invention provides a basis for improving the accuracy of simulating the spin coherence properties of materials with complex atomic defect color centers by constructing an intracrystalline magnetic field.

[0115] Compared with the prior art, the method for constructing an intracrystalline magnetic field of complex atomic defects provided by the present invention has the following beneficial effects:

[0116] 1. The present invention introduces defects by performing stacking faults on the supercell and removing the corresponding atoms, taking into account the complexity of the influence of the intracrystalline magnetic field on the spin, and provides a basis for improving the accuracy of the calculation results of the intracrystalline magnetic field.

[0117] 2. The present invention provides a basis for improving the accuracy of simulating the spin coherence properties of materials with complex atomic defect color centers by constructing an intracrystalline magnetic field.

[0118] 3. The present invention screens the spin magnetic moment based on the preset boundary of the supercell. When calculating the magnetic field induction intensity at any point in the supercell, the spin magnetic moment of electrons closer to the point is screened for calculation. While meeting the calculation accuracy, the calculation time is greatly reduced and the efficiency is improved.

[0119] 4. The present invention performs virtual cell mapping according to the coordinates of the calculation boundary. When the calculation point is close to the edge of the supercell, the area beyond the supercell range in the hexahedron region is mapped to the corresponding area of ​​the supercell, thereby improving the accuracy of the calculation results of the intracrystalline magnetic field.

[0120] Those skilled in the art will appreciate that all or part of the process steps of the above-described embodiments can be implemented by instructing related hardware through a computer program, and the program can be stored in a computer-readable storage medium, such as a magnetic disk, an optical disk, a read-only memory, or a random access memory.

[0121] The above description is only a preferred specific embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any changes or substitutions that can be easily thought of by any technician familiar with this technical field within the technical scope disclosed in the present invention should be covered by the scope of protection of the present invention.

Claims

1. A method for constructing an intracrystalline magnetic field of a complex atomic defect, characterized in that: The method comprises the following steps: Determining the atomic type of the crystal, constructing an initial unit cell based on the atomic type and expanding it into a supercell; performing natural isotope substitution in the supercell; performing stacking faults on the supercell and removing corresponding atomic defects; Based on first principles, the structure of the supercell with defects introduced is optimized until the structurally optimized supercell has a stable configuration, thereby obtaining a structurally optimized supercell; Through static electronic structure calculation, the magnetization density distribution data of the supercell after structural optimization is obtained; Calculating the spin magnetic moment distribution of the structurally optimized supercell according to the magnetization density distribution data; According to the spin magnetic moment distribution, the magnetic field induction intensity at any point in the supercell after structural optimization is calculated to construct the magnetic field.

2. The method for constructing an intracrystalline magnetic field of a complex atomic defect according to claim 1, characterized in that: The stacking faults on the supercell and the removal of corresponding atomic defects include: S11, selecting a first position for a stacking fault in the supercell, and translating atomic coordinates at the first position to obtain a stacking fault; S12. Select a second location for atomic removal in the supercell after the stacking fault, and remove corresponding atoms at the second location to introduce defects.

3. The method for constructing an intracrystalline magnetic field of a complex atomic defect according to claim 2, characterized in that: The step of optimizing the structure of the defect-introduced supercell based on first principles until the structurally optimized supercell has a stable configuration includes: S21, setting optimization parameters; S22, performing structural optimization on the supercell with defects introduced using first-principles calculation software according to the optimization parameters; S23, judging whether the structurally optimized supercell has a stable configuration, if so, obtaining the structurally optimized supercell; otherwise, returning to step S12 to change the second position, and executing steps S22 and S23.

4. The method for constructing an intracrystalline magnetic field of a complex atomic defect according to claim 3, characterized in that: The optimization parameters include the limited number of electron steps, the limited number of ion steps, the convergence accuracy of ion steps, and the convergence accuracy of electron steps.

5. The method for constructing an intracrystalline magnetic field of a complex atomic defect according to claim 4, characterized in that: Whether the supercell after structural optimization has a stable configuration is determined by judging whether the absolute value of the energy difference between adjacent ion steps is less than the ion step convergence accuracy.

6. The method for constructing an intracrystalline magnetic field of a complex atomic defect according to claim 4, characterized in that: The magnetization density distribution data of the supercell after structural optimization obtained by static electronic structure calculation includes: Step S31: Keep the k-point setting and convergence accuracy unchanged, and set the spin-orbit coupling parameters; Step S32: setting the number of ion steps to 0, using first-principles calculation software based on spin-orbit coupling parameters, obtaining the energy corresponding to the supercell through electron steps; iterating the electron steps until the electronic structure of the supercell converges; Step S33: outputting the magnetization density distribution data corresponding to the electronic structure convergence of the supercell.

7. The method for constructing an intracrystalline magnetic field of a complex atomic defect according to claim 6, characterized in that: The energy corresponding to the current electron step is compared with the energy corresponding to the electron step of the previous iteration. If the absolute value of the difference between the two is less than the electron step convergence accuracy, it is determined that the electronic structure of the supercell is converged.

8. The method for constructing an intracrystalline magnetic field of a complex atomic defect according to claim 1, wherein: The spin magnetic moment distribution of the optimized supercell is calculated using the following formula: Among them, g e is the electron g factor, which is approximately 2.002319; μ B is the Bohr magneton; m is the magnetization density distribution; V FFT is the total number of FFT grids; is the spin angular momentum vector.

9. The method for constructing an intracrystalline magnetic field of a complex atomic defect according to claim 1, characterized in that: The magnetic field induction intensity at any point in the supercell after structural optimization is calculated using the following formula: Where μ0 is the vacuum permeability, is the spin magnetic moment distribution, is the vector from the spin magnetic moment to any point in the supercell, and r is the distance from the spin magnetic moment to any point in the supercell.

10. The method for constructing an intracrystalline magnetic field of a complex atomic defect according to claim 1, characterized in that: The constructing an initial unit cell based on the atomic type and expanding it into a supercell comprises: Setting crystal lattice parameters and atomic coordinates based on the atomic type, and constructing an initial unit cell according to the crystal lattice parameters and atomic coordinates; The initial unit cell is repeatedly expanded to obtain a supercell.

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