Method for screening zinc-iron alloy corrosion-resistant complexing agent based on density functional theory

Abstract

The invention aims to provide a method for screening a zinc-iron alloy corrosion-resistant complexing agent based on a density functional theory aiming at the problems that the existing corrosion-resistant coating design depends on a large number of experiments, the trial and error cost is high and the mechanism is not clear. According to the method, the computational chemistry and wave function analysis technology is utilized, structural modeling, energy decomposition and weak interaction analysis of the metal-complexing agent complex system are completed on a computer, quantitative evaluation is conducted on the coordination stability and electronic structure characteristics of different metal-complexing agent systems under the condition that actual electroplating or corrosion experiments are not needed, and the method has the advantages of being high in repeatability and good in repeatability. According to the method, a plating layer system with relatively high corrosion-resistant potential is predicted and screened, the problems of low efficiency, long period and lack of molecular scale mechanism support in traditional process optimization are solved, and a corrosion-resistant system theoretical design and complexing agent screening method which is based on molecular modeling, good in universality, high in efficiency and low in cost is established.

Description

Technical Field

[0001] This invention relates to a method for screening corrosion-resistant complexing agents for zinc-iron alloys based on density functional theory, belonging to the field of quantum chemical calculation. Background Technology

[0002] Metal substrates are prone to electrochemical corrosion in atmospheric, marine, and industrial environments. To improve service life, coatings are commonly used in engineering to construct corrosion-resistant protective layers. Traditional coating and electroplating formulations usually rely on experience and extensive testing for optimization. The design of key factors such as complexing agent type, ratio, and environmental pH generally adopts an "experience-based selection + trial and error adjustment" approach, resulting in long development cycles, high costs, and a lack of mechanistic guidance from the microscopic scale.

[0003] Density functional theory (DFT) has become an important tool for studying metal-complexer interactions, interfacial adsorption, and corrosion resistance mechanisms. By establishing models of metal ion-complexer systems and calculating their geometry, interaction energies, orbital energy levels, and weak interactions, the stability and electronic structure characteristics of complexation systems can be evaluated at the molecular scale, providing a theoretical basis for the design of coating systems and plating solution formulations. In existing research, DFT is often used to explain the adsorption behavior of organic corrosion inhibitors on metal surfaces or to analyze the stability of specific metal complexes. However, a unified evaluation process for "metal-complexer systems" is generally lacking, making it difficult to directly compare the corrosion resistance potential of coatings formed under different complexing agent conditions.

[0004] In electroplating and corrosion-resistant coating systems, multidentate complexing agents such as aminocarboxylic acids, hydroxycarboxylic acids, and phosphonates are commonly used to regulate the coordination environment and deposition behavior of metal ions in the plating bath. Existing work on complexing agent selection largely remains at the empirical level. Even when density functional theory calculations are introduced, they are mostly post-hoc mechanistic explanations for specific complexing agents or single systems. There is a lack of a unified calculation process centered on DFT and wavefunction analysis that can quantify the relationship between "metal-complexing agent coordination stability, electronic structure characteristics, and expected coating corrosion resistance," and also a lack of theoretical methods for comparative evaluation and systematic screening of the same metal under different complexing agent conditions.

[0005] Therefore, it is necessary to propose a method for evaluating the structural stability and electronic structure characteristics of metal-complexing agent systems based solely on density functional theory calculations and wave function analysis. This method can also be used to compare and rank the corrosion resistance trends of coatings under different complexing agent conditions. This approach reduces the reliance on extensive experimental trial and error and provides theoretical support for the development of green and controllable coating formulations and the screening of complexing agents. Summary of the Invention

[0006] The purpose of this invention is to address the problems of existing corrosion-resistant coating designs relying on extensive experiments, high trial-and-error costs, and unclear mechanisms, by providing a method for screening zinc-iron alloy corrosion-resistant complexing agents based on density functional theory. This method utilizes computational chemistry and wavefunction analysis techniques to perform structural modeling, energy decomposition, and weak interaction analysis of metal-complexing agent complex systems on a computer. Without requiring actual electroplating or corrosion experiments, it quantitatively evaluates the coordination stability and electronic structure characteristics of different metal-complexing agent systems, and predicts and screens coating systems with high corrosion resistance potential. This solves the problems of low efficiency, long cycle time, and lack of molecular-scale mechanistic support in traditional process optimization, establishing a molecular modeling-based theoretical design and complexing agent screening method for corrosion-resistant systems that is universal, efficient, and low-cost.

[0007] To achieve the above objectives, the present invention provides the following technical solution: This invention discloses a method for screening corrosion-resistant complexing agents for zinc-iron alloys based on density functional theory, comprising the following steps: S1 Metal System and Complexing Agent Selection: Based on the theoretical model proposed in this invention, a metal-complexing agent structure suitable for corrosion-resistant coating systems is independently designed and constructed. The metal system is the metal ion of the target metal, and the complexing agent structure is composed of complexing agent anions with coordination ability. Generation of the initial coordination structure of S2: A three-dimensional coordination structure model of the metal-complexing agent complex was constructed with the assistance of molecular modeling and molecular visualization software. The initial structure was solvated, hydrogen was added, and the charge and valence states were set to obtain the initial coordination model required for theoretical calculation. Construction of the local coordination environment in step S3: Based on the model obtained in step S2, the local coordination environment of the metal-complexing agent complex is constructed to form a metal-complexing agent local coordination model for quantum chemical calculations; Design and modeling of the S4 computational model: The local coordination model of the metal-complexing agent was edited using molecular modeling software to determine the coordination number, coordination mode and initial bond length, and to generate an input model suitable for quantum chemical calculations; S5 Geometric Structure Optimization: Using quantum chemical calculation software, under the density functional theory method and the basis set level applicable to transition metal coordination systems, the metal-complexer local coordination model is structurally optimized using the keyword opt until the self-consistent field energy and geometric parameters meet the predetermined convergence criteria. S6 Calculation: Based on the optimized structure obtained in step S5, single-point energy calculation is performed to decompose the total interaction energy of the metal-complexing agent system and obtain the energy components of electrostatic interaction energy, Pauli repulsion energy, orbital interaction energy, electronic correlation energy and dispersion energy. S7 Orbital and Weak Interaction Analysis: Based on the wave function information obtained in step S6, frontier orbital analysis is performed on the metal-complexing agent system to obtain the frontier orbital energy levels, band gaps and orbital spatial distribution. Weak interaction analysis methods based on electron density or its gradient are used to identify weak interaction regions such as hydrogen bonds, electrostatic interactions and van der Waals interactions in the system, and corresponding visual isosurface maps or contour maps are obtained. Construction of S8 corrosion-resistant coating design indices: Based on the energy decomposition results, frontier orbital energy levels, band gaps, and weak interaction isosurface plots obtained in steps S6 and S7, the types and intensities of various interactions in the metal-complexing agent complexation model are analyzed. A comprehensive evaluation function with coordination stability index and weak interaction integrity index as the core is established. Based on the comprehensive evaluation function, the corrosion resistance performance of different metal-complexing agent systems is ranked and screened.

[0008] As a preferred embodiment: in step S1 The metal system is preferably ferrous ions, which are used to characterize the complexation behavior of ferrous ions and complexing agents in zinc-iron alloy plating solutions, and serve as the theoretical basis for the design of zinc-iron alloy corrosion-resistant coatings. The complexing agent is preferably ethylenediaminetetraacetic acid (EDTA) anion, and a water molecule is further introduced into its coordination shell to simulate the solution environment, thereby constructing a ferrous-EDTA complex system.

[0009] As a preferred embodiment: In step S2, the three-dimensional molecular model is used to autonomously construct an initial coordination structure model of the ferrous-ethylenediaminetetraacetic acid complex using Mercury 3.6 visualization software. The initial model is then subjected to solvation, hydrogen supplementation, and setting of total charge and valence state, which serves as the input structure for subsequent theoretical calculations.

[0010] As a preferred embodiment: In step S3, based on the three-dimensional structure obtained in step S2, a local coordination environment for the ferrous-ethylenediaminetetraacetic acid complex is constructed. The ligand configuration can effectively encapsulate the metal center and retain the coordinated water molecules in the simulated solution environment, thereby obtaining a local coordination model that is simple in structure, stable and can represent the real complexation state.

[0011] As a preferred option: In step S4, the local coordination model of ferrous iron-ethylenediaminetetraacetic acid is edited again using GaussView 6.0 molecular modeling software. No frozen atoms are set. All atoms in the local coordination model are set as optimizable atoms. The coordination number, coordination mode and initial bond length are determined according to the principle of coordination chemistry.

[0012] As a preferred option: In step S5, the structure of the local coordination model of ferrous iron-ethylenediaminetetraacetic acid is optimized using the quantum chemistry software Gaussian 16.

[0013] As a preferred option: In step S5, density functional theory DFT / M06-2X is used, def2-TZVP basis set is selected, and the keyword opt is used for structural optimization to obtain a stable configuration with the lowest energy.

[0014] As a preferred embodiment: In step S6, the single-point energy calculation adopts the M06-2X / def2-TZVP calculation level and uses DFT-D3 dispersion correction, and the energy convergence criterion is preferably 10⁻. 8 Hartree; After the calculation is complete, the chk file is converted to an fchk file for subsequent wavefunction analysis.

[0015] As a preferred option: In step S6, the energy decomposition analysis is performed by the sobEDA energy decomposition program, which decomposes the total interaction energy of the ferrous-ethylenediaminetetraacetic acid complex system into components such as electrostatic interaction energy, Pauli mutual repulsion energy, orbital interaction energy, correlation energy and dispersion energy, and uses the sum of electrostatic interaction energy and orbital interaction energy as the main stabilization index.

[0016] As a preferred embodiment: In step S7, the Multiwfn wavefunction analysis program is used to perform frontier orbital and weak interaction analysis on the fchk file, calculate the HOMO, LUMO energy levels and band gap of the ferrous-ethylenediaminetetraacetic acid complex system, obtain the weak interaction function through the IMH and RDG methods, and plot the corresponding weak interaction isosurface in the visualization molecular dynamics program (VMD).

[0017] As a preferred option: In step S8, based on the energy decomposition results, frontier orbital energy levels, band gaps, and weak interaction isosurface maps obtained in steps S6 and S7, the types and strengths of various interactions in the complexation model of ferrous iron-ethylenediaminetetraacetic acid complex are studied, a comprehensive evaluation function with coordination stability index and weak interaction integrity index as the core is established, and the comprehensive evaluation results are compared with the calculation results of other metal-complexing agent systems to complete the screening of complexing agents for zinc-iron alloy corrosion-resistant coatings.

[0018] This invention utilizes molecular modeling and density functional theory to computationally study metal-complexing agent systems. First, quantum chemistry software is used to optimize the geometric structure and calculate single-point energies of the system, obtaining structural and energy information including wavefunctions. Then, combined with energy decomposition analysis programs (e.g., sobEDA) and wavefunction analysis tools (e.g., Multiwfn), the corresponding coordination interaction energies, frontier orbital levels, and weak interaction characteristics are systematically analyzed. Using the calculation results, comprehensive evaluation indices such as coordination stability, electronic structure stability, and weak interaction integrity are constructed to evaluate and screen suitable metal-complexing agent systems for corrosion-resistant coating design, and to compare the corrosion resistance potential of coatings formed by the same metal under different complexing agent conditions. This method eliminates the need for actual electroplating and corrosion experiments, enabling preliminary design and optimization of corrosion-resistant coatings on a computer. It provides theoretical reference for optimizing plating solution formulations and initially selecting process parameters, thereby reducing the number of experiments, shortening the development cycle, lowering costs, and mitigating the environmental burden that may result from experiments.

[0019] Compared with the prior art, the beneficial effects of the present invention are: 1) This invention applies quantum chemical calculations and wave function analysis to optimize the geometry and calculate the energy of metal-complexing agent systems at the level of density functional theory with dispersion correction and medium-to-high precision basis sets. It can obtain the geometric configuration and energy information of the complexing system relatively accurately and reliably. 2) This invention, through energy decomposition analysis and visualization of weak interactions, can quantitatively distinguish the contributions of electrostatic interactions, Pauli repulsion, orbital interactions, and dispersion to the coordination stability of metal-complexing agents, and identify weak interaction regions such as hydrogen bonds, electrostatics, and van der Waals interactions. Based on this, a comprehensive evaluation index for coordination stability, electronic structure stability, and the integrity of weak interactions is constructed, which can intuitively reflect the stability of the complexing system and the quality of the coordination environment, providing clear criteria for selecting metal-complexing agent combinations that are conducive to obtaining dense, stable, and corrosion-resistant coatings. 3) The entire process of this invention is implemented by computer, avoiding experiments, reducing R&D costs, and ensuring safety and reliability; 4) The entire process of this invention does not involve experiments, thus avoiding environmental pollution and conforming to the concept of green and environmentally friendly development; 5) The metal-complexing agent system analysis and evaluation process based on density functional theory proposed in this invention has good versatility. Under the premise of keeping the calculation process and evaluation index system unchanged, it can be extended to complexation systems formed by the same metal ion and different complexing agents, as well as different metal-multidentate complexing agent systems. It can provide a unified theoretical evaluation and comparison of corrosion-resistant coating schemes of different complexing agents and different metal systems, and provide a generalizable calculation method basis for the green corrosion-resistant design of various metal coating systems. Attached Figure Description

[0020] Figure 1 A schematic diagram of the optimized three-dimensional structure of the ferrous iron-ethylenediaminetetraacetic acid complex; Figure 2 A bar chart showing the energy decomposition of the ferrous iron-ethylenediaminetetraacetic acid complex; Figure 3 is a schematic diagram of the HOMO and LUMO frontal orbit distribution of the ferrous iron-ethylenediaminetetraacetic acid complex. Figure 4 is a schematic diagram of the weak interaction isosurface of the ferrous iron-ethylenediaminetetraacetic acid complex. Detailed Implementation

[0021] The present invention will be further described below with reference to the accompanying drawings and specific embodiments.

[0022] This invention provides a method for screening corrosion-resistant complexing agents for zinc-iron alloys based on density functional theory, comprising the following steps: S1 Metal System and Complexing Agent Selection: Based on the theoretical model proposed in this invention, a metal-complexing agent structure suitable for corrosion-resistant coating systems is independently designed and constructed. The metal system is the metal ion of the target metal, and the complexing agent structure is composed of complexing agent anions with coordination ability. Generation of the initial coordination structure of S2: A three-dimensional coordination structure model of the metal-complexing agent complex was constructed with the assistance of molecular modeling and molecular visualization software. The initial structure was solvated, hydrogen was added, and the charge and valence states were set to obtain the initial coordination model required for theoretical calculation. Construction of the local coordination environment in step S3: Based on the model obtained in step S2, the local coordination environment of the metal-complexing agent complex is constructed to form a metal-complexing agent local coordination model for quantum chemical calculations; Design and modeling of the S4 computational model: The local coordination model of the metal-complexing agent was edited using molecular modeling software to determine the coordination number, coordination mode and initial bond length, and to generate an input model suitable for quantum chemical calculations; S5 Geometric Structure Optimization: Using quantum chemical calculation software, under the density functional theory method and the basis set level applicable to transition metal coordination systems, the metal-complexer local coordination model is structurally optimized using the keyword opt until the self-consistent field energy and geometric parameters meet the predetermined convergence criteria. S6 Calculation: Based on the optimized structure obtained in step S5, single-point energy calculation is performed to decompose the total interaction energy of the metal-complexing agent system and obtain the energy components of electrostatic interaction energy, Pauli repulsion energy, orbital interaction energy, electronic correlation energy and dispersion energy. S7 Orbital and Weak Interaction Analysis: Based on the wave function information obtained in step S6, frontier orbital analysis is performed on the metal-complexing agent system to obtain the frontier orbital energy levels, band gaps and orbital spatial distribution. Weak interaction analysis methods based on electron density or its gradient are used to identify weak interaction regions such as hydrogen bonds, electrostatic interactions and van der Waals interactions in the system, and corresponding visual isosurface maps or contour maps are obtained. Construction of S8 corrosion-resistant coating design indices: Based on the energy decomposition results, frontier orbital energy levels, band gaps, and weak interaction isosurface plots obtained in steps S6 and S7, the types and intensities of various interactions in the metal-complexing agent complexation model are analyzed. A comprehensive evaluation function with coordination stability index and weak interaction integrity index as the core is established. Based on the comprehensive evaluation function, the corrosion resistance performance of different metal-complexing agent systems is ranked and screened. Example

[0023] 1. The divalent iron-ethylenediaminetetraacetic acid complex system, which is closely related to the corrosion-resistant coating of zinc-iron alloy, was selected. Based on the principle of coordination chemistry, its structural model was independently constructed as the initial structural basis for theoretical calculations. 2. Using GaussView 6.0 software, the ferrous iron-ethylenediaminetetraacetic acid complex model constructed in step 1 was converted into a three-dimensional molecular form. A preliminary structure check was performed, redundant molecules and pairs of ions were removed, and unreasonable bond lengths and bond angles were corrected to form a reasonable initial coordination structure model. 3. Based on the three-dimensional structure, the ferrous iron-ethylenediaminetetraacetic acid complex molecule was further constructed as a local coordination model, hydrogen atoms were added, the total charge was set to -2, and the spin multiplicity was set to 1 to ensure that the model meets the set electronic state requirements; 4. Import the local coordination model of the ferrous iron-ethylenediaminetetraacetic acid complex obtained in step 3 into Gaussian 16 quantum chemistry software to establish a computational model. Do not set frozen atoms; set all atoms in the model as optimizable atoms. Use the M06-2X functional and def2-TZVP basis set, and use the opt keyword for geometry optimization to obtain the stable configuration with the lowest energy. 5. Based on the optimized structure, single-point energy calculations were performed using the M06-2X / def2-TZVP computational level combined with DFT-D3 dispersion correction, with the energy convergence threshold set to 10⁻. 8 Hartree. After calculation, a chk file containing wavefunction information is obtained, which is then converted to an fchk file for subsequent wavefunction analysis. The single-point energy calculation results are read using the sobEDA energy decomposition analysis program to decompose the total interaction energy of the ferrous iron-ethylenediaminetetraacetic acid (EDTA) complex system. The total interaction energy of the EDTA complex is –1176.50 kcal·mol⁻¹, where the electrostatic interaction energy Eels The Pauli mutual repulsion energy is -1019.26 kcal·mol⁻¹. rep The orbital interaction energy is 307.00 kcal·mol⁻¹, and the orbital interaction energy is E. orb The dispersion correction is -355.06 kcal·mol⁻¹, E dc It is –0.06 kcal·mol⁻¹. Furthermore, the energy decomposition analysis also yielded the exchange interaction energy E. x DFT correlation energy E DFTc Dispersion correction E dc And the total correlation energy E, which is composed of the DFT correlation energy and the dispersion correction. c Isoenergetic components were used to further analyze the electronic structure characteristics of the ferrous iron-ethylenediaminetetraacetic acid (EDTA) complex system. The results showed that electrostatic interactions and orbital interactions were the main stabilizing terms, while Pauli repulsion was the main destabilizing term. The overall interaction energy was relatively large, indicating that a stable coordination structure was formed between the iron ion and EDTA.

[0024] 6. Import the fchk file obtained in step 5 into the Multiwfn wavefunction analysis program to perform frontier orbital analysis on the ferrous-ethylenediaminetetraacetic acid complex system, calculate the HOMO level, LUMO level, and band gap ΔE, and obtain the compositional distribution of each orbital on the iron atom and ethylenediaminetetraacetic acid atom. Figure 3(a) is a schematic diagram of the HOMO orbital distribution. It can be seen that the HOMO is mainly distributed on the carboxylate oxygen atom on the ligand side and near the iron-oxygen bond connected to the iron atom. Only a small amount of orbital density is distributed on the iron atom, and almost none is distributed on the methylene carbon of the ethylenediamine framework. This indicates that the p orbitals of the ligand carboxylate oxygen atom are dominant, with a small amount of d orbital components from the iron atom. Overall, it shows the coordination characteristics of the ligand supplying electrons to the metal center. Figure 3(b) shows a schematic diagram of the LUMO orbital distribution. It can be seen that the LUMO orbitals are mainly concentrated on the iron-oxygen coordination bond direction on the other side and outside the adjacent carboxylic acid group. The orbitals form a continuous distribution between the iron atom and some ligand oxygen atoms, extending into the solution-side space. This indicates that the lowest unoccupied orbitals are mainly composed of the d orbitals of the iron atom and the p orbitals of the carboxylic acid oxygen atoms, acting as acceptor orbitals in collaboration between the metal center and the ligand. When the system undergoes electron injection or reduction, electrons preferentially fill these orbitals, achieving electron rearrangement along the iron-oxygen coordination axis and the carboxylic acid group direction. This adjusts the valence state of the metal center while maintaining the coordination framework, providing a potential electron channel for iron ions in the corrosion-resistant coating to participate in the cathode process. Combining the spatial distributions of HOMO and LUMO, it can be seen that the frontier orbitals are concentrated in the iron-oxygen coordination framework and the adjacent carboxylic acid group region. The ethylenediamine framework basically does not participate in the frontier orbital composition, indicating that the key electronic behavior of the ferrous iron-ethylenediaminetetraacetic acid complex system is controlled by the iron-oxygen coordination fragments. The ligand framework mainly plays a role in configurational support and spatial containment, which is conducive to forming a stable and controllable coordination environment. 7. In Multiwfn, weak interaction functions of IGMH and RDG were constructed based on the fchk file to analyze weak interactions such as hydrogen bonding, electrostatic interaction, and van der Waals interaction in the ferrous-ethylenediaminetetraacetic acid complex system. The isosurface data was then imported into the VMD visualization molecular dynamics program to plot the isosurfaces. Figure 4(a) shows a schematic diagram of the IGMH isosurface. It can be seen that the isosurfaces surrounding the iron atom and its six coordinated oxygen atoms are continuously distributed, with green and light blue as the main colors. Only in local iron-oxygen bonds are there strong attraction in the light blue areas. There are almost no large red areas, indicating that there is no significant repulsive stacking inside the coordination region. There is a continuous medium-strength weak interaction "shell" between iron and multiple carboxylic acid oxygen atoms in addition to the main coordination bond, which further enhances the overall rigidity and stability of the coordination environment. Figure 4(b) shows a schematic diagram of the RDG isosurfaces. Spindle-shaped or sheet-like blue and light blue isosurfaces can be observed in multiple C–H…O and O…O neighboring regions, indicating multiple hydrogen bonds and strong electrostatic attraction between ligands. Numerous band-shaped or sheet-like green isosurfaces are distributed between the ligand framework and around the ferrous iron-ethylenediaminetetraacetic acid complex, representing widespread van der Waals interactions and loose contacts. Only small red patches appear between a few closely spaced atoms, having a weak impact on the overall structure. Combining the IMH and RDG images, it can be seen that the ferrous iron-ethylenediaminetetraacetic acid complex system forms a continuous weak interaction network outside the main coordination bond through multiple hydrogen bonds, electrostatic attraction, and van der Waals interactions. On the one hand, this helps to lock the ligand configuration, suppress excessive conformational fluctuations, and improve the stability of the complex in solution. On the other hand, it provides a buffer for the migration and electron rearrangement of iron ions in the coordination shell during electroplating, which is beneficial for obtaining a dense, uniform, and less defective corrosion-resistant coating. 8. Based on the energy decomposition results, frontier orbital energy levels, and weak interaction analysis results obtained in steps 5–7, a coordination stability index (based on E0) is constructed. els E orb With –E repThe comprehensive evaluation values ​​of the ferrous iron-ethylenediaminetetraacetic acid (Fe-EDTA) complex system were obtained by combining the comprehensive characterization of the complex with the electronic structure stability index (characterized by parameters such as band gap ΔE) and the weak interaction integrity index (characterized by the connectivity and area of ​​IGMH and RDG isosurfaces). These indices were then normalized. The evaluation results show that, under the set coordination mode and charge state, the Fe-EDTA complex system has a high comprehensive evaluation value, indicating that this complex state, while balancing coordination stability and moderate electronic activity, forms a relatively complete weak interaction network, making it suitable as a complexation state model for iron ions in zinc-iron alloy corrosion-resistant coatings. For complex systems formed by the same metal ion and other candidate complexing agents, steps 1-8 above can be repeated as described in this embodiment to obtain their respective comprehensive evaluation values. By comparing the evaluation results under different complexing agent conditions, the corrosion resistance trends of coatings formed by different complexing agents can be qualitatively and semi-quantitatively ranked, providing a theoretical reference for subsequent complexing agent screening, experimental verification of the electroplating system, and process optimization.

Claims

1. A method for screening corrosion resistant complexing agents for zinc-iron alloys based on density functional theory, characterized by, Comprising the following steps: S1 metal system and complexing agent selection: according to the theoretical model proposed in the present application, a metal-complexing agent structure suitable for corrosion-resistant coating system is designed and constructed, wherein the metal system is the metal ion of the target metal, and the complexing agent structure is composed of complexing agent anions with coordination ability; S2 generation of initial coordination structure: a three-dimensional coordination structure model of the metal-complexing agent complex is constructed with the aid of molecular modeling and molecular visualization software, the initial structure is solvated, hydrogen is supplemented, and charge and valence state are set, to obtain an initial coordination model required for theoretical calculation; S3 construction of local coordination environment: on the basis of the model obtained in step S2, the local coordination environment of the metal-complexing agent complex is constructed to form a metal-complexing agent local coordination model for quantum chemical calculation; S4 design and modeling of calculation model: the metal-complexing agent local coordination model is edited using molecular modeling software to determine the coordination number, coordination mode and initial value of bond length, and an input model suitable for quantum chemical calculation is generated; S5 geometry optimization: using quantum chemical calculation software, under the density functional theory method and the basis set level suitable for transition metal coordination system, the metal-complexing agent local coordination model is optimized using the keyword opt until the self-consistent field energy and geometric parameters meet the predetermined convergence criteria; S6 calculation: based on the optimized structure obtained in step S5, single-point energy calculation is performed, the total interaction energy of the metal-complexing agent system is decomposed, and the energy components of electrostatic interaction energy, Pauli repulsion energy, orbital interaction energy, electronic correlation energy and dispersion energy are obtained; S7 orbital and weak interaction analysis: based on the wave function information obtained in step S6, the metal-complexing agent system is analyzed to obtain the front-line orbital energy level, energy gap and orbital spatial distribution, and the weak interaction analysis method based on electron density or its gradient is used to identify the weak interaction regions such as hydrogen bond, electrostatic interaction and van der Waals interaction in the system, to obtain the corresponding visual contour or isogram; S8 construction of corrosion-resistant coating design index: according to the energy decomposition results, front-line orbital energy level, energy gap and weak interaction contour map obtained in steps S6 and S7, the types and strengths of various interactions in the metal-complexing agent complex model are analyzed, a comprehensive evaluation function with coordination stability index and weak interaction integrity index as the core is established, and the corrosion resistance of different metal-complexing agent systems is sorted and selected based on the comprehensive evaluation function.

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