Calculation methods, media, and program products for theoretical simulation of oxygen reduction reactions based on first principles

Abstract

The present invention relates to a theoretical simulation calculation method, medium, and program product of oxygen reduction reaction based on first principles. The simulation calculation method realizes the whole process from disordered structure pretreatment, slab model construction, VASP input file generation, to oxygen reduction reaction energy barrier and overpotential calculation, and differential charge density analysis through an automated process. The method adopts computational hydrogen electrode (CHE) technology, comprehensively considering various reaction mechanisms, such as four-electron process AEM mechanism, OPM mechanism and two-electron process, to accurately calculate the free energy change of each reaction step. Compared with the prior art, the present invention not only improves the calculation efficiency and reduces the operation threshold, but also provides a powerful tool for in-depth understanding of the oxygen reduction reaction mechanism, which is of great significance to the research in the fields of fuel cells and metal-air batteries.

Description

Technical Field

[0001] The present invention relates to the technical field of oxygen reduction reaction theoretical simulation, and in particular to a first-principles-based oxygen reduction reaction theoretical simulation calculation method, medium, and program product. Background Art

[0002] In the fields of materials science and chemistry, the oxygen reduction reaction (ORR) is a key reaction in fuel cells and metal-air batteries, and its efficiency directly affects the performance of energy conversion devices. Traditional experimental methods are often time-consuming and costly. With the development of computational chemistry, first-principles calculations have provided a new approach to understanding and predicting ORR. However, existing computational methods suffer from complex operations and low efficiency, especially when dealing with disordered structures and large-scale calculations.

[0003] Although first-principles calculations can theoretically provide accurate analysis of the ORR reaction mechanism, they face several major challenges in practical applications. First, traditional computational methods are difficult to handle for disordered structures containing fractional occupancy, requiring them to be converted into ordered structures, a tedious process that is prone to errors. Second, the existing computational process lacks automation, making high-throughput calculations difficult to achieve. In addition, for novice researchers, the complex operational procedures and high threshold computational requirements limit the application of this technology. Summary of the Invention

[0004] The purpose of the present invention is to overcome the defects of the above-mentioned prior art and provide a first-principles-based oxygen reduction reaction theoretical simulation calculation method, medium, and program product, which significantly improves the calculation efficiency and operability by automatically processing disordered structures, generating VASP input files, and calculating ORR energy barriers, overpotentials, and differential charge density.

[0005] The purpose of the present invention can be achieved by the following technical solutions:

[0006] A first aspect of the present invention provides a first-principles-based theoretical simulation method for oxygen reduction reaction, comprising the following steps:

[0007] S1. Preprocessing of disordered structures:

[0008] a. Receive a cif file with an unordered structure and score placeholders;

[0009] b. Expand the received cif file to generate an expanded cell structure;

[0010] c. Randomly generate n ordered structures based on the expanded cell structure;

[0011] d. Calculate the electrostatic energy of the system for each ordered structure;

[0012] e. Screening to obtain several ordered structures with the lowest electrostatic energy;

[0013] f. Perform DFT calculation and structural relaxation on the ordered structures obtained by screening to obtain the ordered structure with the lowest total energy;

[0014] S2. Construction of slab model and generation of VASP input file:

[0015] g. Based on the obtained ordered structure with the lowest total energy, a slab model of the material surface is constructed to simulate the oxygen reduction reaction;

[0016] h. Using the slab model, use the Pymatgen library to generate the input file required for VASP calculation, which can be used for first-principles calculation;

[0017] S3: Calculation of the energy barrier and overpotential of the oxygen reduction reaction:

[0018] i. Using the generated VASP input file, calculate the energy barrier and overpotential of the oxygen reduction reaction using the computational hydrogen electrode (CHE) method;

[0019] j. calculating the free energy change for each reaction step of the oxygen reduction reaction to determine the overpotential;

[0020] S4: Calculation of differential charge density:

[0021] k. Based on the calculated structural information of the oxygen reduction reaction intermediates, perform electronic self-consistent calculations on each intermediate, slab model part, and adsorbate part to obtain a charge density file;

[0022] 1. Using the charge density file, call VASPKit software to calculate the differential charge density and describe the change in charge distribution in the system to intuitively show the redistribution of charge during the oxygen reduction reaction.

[0023] Furthermore, in S1, the conditions for performing the cell expansion process on the received cif file include:

[0024] Ensure that the total number of each type of atom in the expanded unit cell is an integer.

[0025] Furthermore, in S2, the required input files include POSCAR, INCAR, KPOINTS, and POTCAR files.

[0026] Furthermore, in S3, the free energy-related parameters include: zero-point energy, change in total ground state energy, temperature, change in entropy, and electrode potential.

[0027] Furthermore, in step g to step l, the three reaction mechanisms of four-electron process AEM mechanism, four-electron process OPM mechanism and two-electron process are respectively carried out.

[0028] Furthermore, the electron transfer process of the AEM mechanism is:

[0029] *+O2+H + +e - →*OOH

[0030] *OOH+H + +e - →*O+H2O

[0031] *O+H + +e - →*OH

[0032] *OH+H + +e - →*+H2O

[0033] The electron transfer process of the OPM mechanism is:

[0034] **+O2→*OO*

[0035] *OO*+H + +e - →*OH*O

[0036] *OH*O+H + +e - →*O*+H2O

[0037] *O*+H + +e - →*OH

[0038] *OH+H + +e - →**+H2O

[0039] The electron transfer in a two-electron process is:

[0040] *+O2+H + +e - →*OOH

[0041] *OOH+H + +e - →*O+H2O2

[0042] *O, *OH, and *OOH are reaction intermediates adsorbed on the catalyst surface in the slab model.

[0043] Furthermore, in S3, the formula used to calculate the free energy change of each reaction step is as follows:

[0044] ΔG=ΔZPE+ΔE-T×ΔS+ΔGU

[0045] Where ΔZPE is the zero-point energy, ΔE is the change in total ground-state energy, T is the temperature (298 K), ΔS is the change in entropy, and ΔGU = eU, where U is the electrode potential. The zero-point energy and entropy of the intermediates are obtained by calculating the vibrational frequencies, so the total energy and zero-point energy of each intermediate need to be calculated. The overpotential is the largest of all reaction energy barriers.

[0046] Furthermore, in S4, the differential charge density is calculated based on the obtained charge density file, wherein the differential charge density Δρ is calculated by subtracting the charge density ρslab of the slab part and the charge density ρabsorbate of the adsorbate part from the charge density ρ of the system, that is, Δρ=ρ-ρslab-ρabsorbate.

[0047] In a second aspect, the present invention provides a computer-readable storage medium having a computer program stored thereon, which, when executed by a processor, implements the steps of the above-mentioned first-principles-based theoretical simulation calculation method for oxygen reduction reaction.

[0048] In a second aspect, the present invention provides a computer program product, comprising a computer program, which, when executed by a processor, implements the steps of the above-mentioned first-principles-based theoretical simulation calculation method for oxygen reduction reaction.

[0049] Compared with the prior art, the present invention has the following technical advantages:

[0050] 1) The first-principles theoretical calculation method for the oxygen reduction reaction provided by this invention significantly improves the accuracy and efficiency of theoretical calculations through automated preprocessing steps, precise slab model construction, and efficient differential charge density calculations. This method not only lowers the operational threshold, enabling high-throughput calculations, but also provides important theoretical support for experimental design and material selection by providing a deeper understanding of the microscopic mechanism of the oxygen reduction reaction.

[0051] 2) Furthermore, by integrating advanced computational hydrogen electrode (CHE) methods with differential charge density analysis, this invention accurately predicts the energy barrier and overpotential of the oxygen reduction reaction, providing key guidance for optimizing the performance of fuel cells and metal-air batteries. The implementation of this method will help accelerate the discovery and development of new energy materials, thereby promoting innovation and development in energy conversion technologies.

[0052] 3) Finally, the method of this invention significantly reduces tedious manual operations by providing a complete computational workflow and automated scripts, saving researchers valuable time. This streamlined workflow not only improves the reproducibility and reliability of computations but also, by lowering the barrier to entry for novices, promotes knowledge sharing and technology dissemination within the research community, potentially accelerating the pace of scientific discovery. BRIEF DESCRIPTION OF THE DRAWINGS

[0053] Figure 1 Schematic diagram of the flow chart of the theoretical simulation calculation method of oxygen reduction reaction based on first principles in the present invention. DETAILED DESCRIPTION

[0054] This method significantly improves computational efficiency and operability by automating the processing of disordered structures, generating VASP input files, and calculating ORR energy barriers, overpotentials, and differential charge density. This method not only simplifies the workflow and reduces the need for user experience, but also enables high-throughput calculations by providing Python scripts and automated processes, providing a powerful theoretical tool for material design and battery performance optimization.

[0055] The present invention will be described in detail below with reference to the accompanying drawings and specific embodiments. Component models, material names, connection structures, control methods, algorithms, and other features not explicitly described in this technical solution are considered common technical features disclosed in the prior art.

[0056] Example 1

[0057] The first aspect of the present invention provides a theoretical simulation calculation method for oxygen reduction reaction based on first principles, see Figure 1 , including the following steps:

[0058] S1. Preprocessing of disordered structures:

[0059] a. Receive a cif file with an unordered structure and score placeholders;

[0060] b. Expand the received cif file to generate an expanded cell structure;

[0061] c. Randomly generate n ordered structures based on the expanded cell structure;

[0062] d. Calculate the electrostatic energy of the system for each ordered structure;

[0063] e. Screening to obtain several ordered structures with the lowest electrostatic energy;

[0064] f. Perform DFT calculation and structural relaxation on the ordered structures obtained by screening to obtain the ordered structure with the lowest total energy;

[0065] In S1, the conditions for expanding the received cif file include:

[0066] Ensure that the total number of each type of atom in the expanded unit cell is an integer.

[0067] The detailed principle analysis of this step is as follows:

[0068] a. Receive a CIF file with fractional placeholders for a disordered structure: In materials science, crystal structures are often represented using CIF (Crystallographic Information File) files. CIF files are text files containing crystal structure data and follow the standards of the International Union of Crystallography (IUCr). Disordered structures refer to structures where the positions of certain atoms in the crystal structure are uncertain or have multiple possible arrangements. This is represented in CIF files using fractional placeholders.

[0069] b. Expand the received CIF file to generate an expanded structure: Unit cell expansion involves replicating the crystal unit cell multiple times in three-dimensional space to ensure that all atoms in the unit cell have integer coordinates. This is done to convert the disordered structure into an ordered structure that can be processed by the computational software.

[0070] c. Randomly generate n ordered structures based on the expanded cell structure: Since the atomic positions in the disordered structure are fractionally occupied, multiple possible ordered structures can be randomly generated after cell expansion. This step is to create multiple possible crystal structure models for further calculation and analysis.

[0071] d. Calculate the electrostatic energy of each ordered structure: Electrostatic energy refers to the energy generated by the electrostatic forces between atoms in a crystal structure. Calculating the electrostatic energy of each ordered structure is to assess its stability.

[0072] e. Screening for several ordered structures with the lowest electrostatic energy: The structure with the lowest electrostatic energy usually corresponds to the most stable crystal structure. These structures are screened to find the crystal structure most likely to be observed in the experiment.

[0073] f. Perform DFT calculations and structural relaxation on the screened ordered structures to identify the ordered structure with the lowest total energy: DFT (Density Functional Theory) is a method for calculating electronic structure in quantum mechanics and is used to predict the physical and chemical properties of materials. Structure relaxation is the process of adjusting atomic positions in a DFT calculation until the system reaches its lowest energy point. This step aims to find the most energetically stable crystal structure.

[0074] S2. Construction of slab model and generation of VASP input file:

[0075] g. Based on the obtained ordered structure with the lowest total energy, a slab model of the material surface is constructed to simulate the oxygen reduction reaction;

[0076] h. Using the slab model, use the Pymatgen library to generate the input file required for VASP calculation, which can be used for first-principles calculation;

[0077] In S2, the required input files include POSCAR, INCAR, KPOINTS, and POTCAR files.

[0078] The detailed principle analysis of this step is as follows:

[0079] g. Based on the obtained ordered structure with the lowest total energy, a slab model is constructed to simulate the material surface where the oxygen reduction reaction occurs: In materials science, a slab model is a computational model used to simulate solid surfaces and interfaces. This model typically slices the solid surface into thin slices along a certain direction, leaving sufficient vacuum regions on one or both sides of the slice to reduce artificial interactions caused by periodic boundary conditions.

[0080] h. Using the slab model, use the Pymatgen library to generate the input files required for VASP calculations. Pymatgen (Python Materials Genomics) is a powerful open-source Python library for materials analysis. It provides extensive input / output support, including support for file formats required for VASP calculations. Pymatgen can automatically generate the input files required for VASP calculations, such as POSCAR, INCAR, KPOINTS, and POTCAR.

[0081] Slab model: A computational model used to simulate material surfaces, commonly used in computational catalysis and surface science.

[0082] VASP: Vienna Ab-initio Simulation Package, Vienna Ab-initio Simulation Package, is a widely used first-principles calculation software for simulating electronic structure properties and molecular dynamics.

[0083] Pymatgen: Python Materials Genomics, Python Materials Genomics, an open source Python library for materials analysis. In S2, the required input files include:

[0084] POSCAR: A file used to describe the crystal structure in VASP calculations, containing information such as unit cell parameters, atomic species, and coordinates.

[0085] INCAR: A file used to specify calculation parameters in VASP calculations, such as exchange-correlation functionals, electronic convergence criteria, etc.

[0086] KPOINTS: A file used to specify k-point sampling in VASP calculations, which affects the calculation of properties such as band structure and state density.

[0087] POTCAR: A file used in VASP calculations to describe the pseudopotential information of atoms, including the electronic structure of atoms and the treatment of core electrons.

[0088] S3: Calculation of the energy barrier and overpotential of the oxygen reduction reaction:

[0089] i. Using the generated VASP input file, calculate the energy barrier and overpotential of the oxygen reduction reaction using the Computational Hydrogen Electrode (CHE) method. The Computational Hydrogen Electrode (CHE) method is a theoretical method used to simulate electrochemical interfaces and calculate the thermodynamic parameters of electrochemical reactions. By simulating the adsorption and desorption of hydrogen atoms on the electrode surface, the CHE method can provide a reference system for other electrochemical reactions, thereby calculating the relative potentials of other reactions.

[0090] j. calculating the free energy change for each reaction step of the oxygen reduction reaction to determine the overpotential;

[0091] In S3, the free energy-related parameters include: zero-point energy, change in total ground state energy, temperature, change in entropy, and electrode potential.

[0092] In step g to step l, the three reaction mechanisms are respectively carried out according to the four-electron process AEM mechanism, the four-electron process OPM mechanism, and the two-electron process.

[0093] In S3, the free energy change of each reaction step is calculated using the following formula:

[0094] ΔG=ΔZPE+ΔE-T×ΔS+ΔGU

[0095] Where ΔZPE is the zero-point energy, ΔE is the change in total ground-state energy, T is the temperature (298 K), ΔS is the change in entropy, and ΔGU = eU, where U is the electrode potential. The zero-point energy and entropy of the intermediates are obtained by calculating the vibrational frequencies, so the total energy and zero-point energy of each intermediate need to be calculated. The overpotential is the largest of all reaction energy barriers.

[0096] S4: Calculation of differential charge density:

[0097] k. Based on the calculated structural information of the oxygen reduction reaction intermediates, perform electronic self-consistent calculations on each intermediate, slab model part, and adsorbate part to obtain a charge density file;

[0098] 1. Using the charge density file, call VASPKit software to calculate the differential charge density and describe the change in charge distribution in the system to intuitively show the redistribution of charge during the oxygen reduction reaction.

[0099] Among them: The electron transfer process of the AEM mechanism is:

[0100] *+O2+H + +e - →*OOH

[0101] *OOH+H + +e - →*O+H2O

[0102] *O+H + +e - →*OH

[0103] *OH+H + +e - →*+H2O

[0104] The electron transfer process of the OPM mechanism is:

[0105] **+O2→*OO*

[0106] *OO*+H + +e - →*OH*O

[0107] *OH*O+H + +e - →*O*+H2O

[0108] *O*+H + +e - →*OH

[0109] *OH+H + +e - →**+H2O

[0110] The electron transfer in a two-electron process is:

[0111] *+O2+H + +e - →*OOH

[0112] *OOH+H + +e - →*O+H2O2

[0113] *O, *OH, and *OOH are reaction intermediates adsorbed on the catalyst surface in the slab model.

[0114] In S4, the differential charge density is calculated based on the obtained charge density file, where the differential charge density Δρ is calculated by subtracting the charge density ρslab of the slab part and the charge density ρabsorbate of the adsorbate part from the charge density ρ of the system, that is, Δρ=ρ-ρslab-ρabsorbate.

[0115] Example 2

[0116] The present embodiment provides a computer-readable storage medium, on which a special computer program is stored, which is intended to realize a theoretical simulation calculation method of oxygen reduction reaction (ORR) based on first principles by processor execution. The oxygen reduction reaction is efficiently and accurately simulated theoretically, thereby providing a powerful tool for the research of materials science and energy conversion technology. The computer program includes all the instruction sets required for implementing the above method, including the pre-processing of disordered structure, the construction of slab model, the generation of VASP input file, the calculation of energy barrier and overpotential of oxygen reduction reaction, and the key steps of calculation of differential charge density. When the processor executes these instructions, it can automatically complete the whole process from receiving disordered structure cif file with fractional occupancy, to generating cell structure, calculating electrostatic energy, screening ordered structure, building slab model, generating VASP input file, until calculating reaction energy barrier and overpotential. In addition, the program can also be calculated and analyzed according to the mechanism of oxygen reduction reaction, such as four-electron process AEM mechanism, four-electron process OPM mechanism and two-electron process. By invoking the VASPKit software, the program can also calculate differential charge density, providing an intuitive charge distribution image for understanding the reaction mechanism and the interaction between catalysts and reactants. The design of this computer-readable storage medium not only improves the efficiency and accuracy of theoretical calculations of the oxygen reduction reaction, but also simplifies operations through automated processes, reducing the requirements for user experience. This enables more researchers to utilize this tool, promoting scientific discovery and technological innovation in related fields.

[0117] Example 3

[0118] The present embodiment provides an advanced computer program product, which includes a specially designed computer program that is intended to complete the various steps of the theoretical simulation calculation method of the oxygen reduction reaction (ORR) based on first principles through processor execution. This innovative program product greatly improves the efficiency and accuracy of theoretical calculations in an automated manner, and is of great significance to the research and development of materials science, energy conversion technology, and electrochemical catalysts. The computer program integrates multiple key links such as disordered structure pretreatment, slab model construction, VASP input file generation, oxygen reduction reaction energy barrier and overpotential calculation, and differential charge density calculation. When the processor runs this program, it can automatically execute the complete process from receiving the cif file of the disordered structure until all necessary calculation steps are completed and the theoretical simulation results of the oxygen reduction reaction are output. The design of the program takes into account a variety of oxygen reduction reaction mechanisms, including the AEM mechanism of the four-electron process, the OPM mechanism, and the two-electron process, to ensure the comprehensiveness and applicability of the calculation results. In addition, the program can also call vaspkit software to calculate the differential charge density, providing detailed information required for a deep understanding of the reaction mechanism. The development of this computer program makes complex first-principles calculations easier to manage and operate, reducing the need for specialized expertise and enabling more researchers to conveniently conduct theoretical simulations of the oxygen reduction reaction. Furthermore, the program's high efficiency enables high-throughput computations, helping to accelerate the discovery of new materials and advances in energy conversion technologies.

[0119] The above description of the embodiments is intended to facilitate understanding and use of the invention by those skilled in the art. It will be apparent that those skilled in the art can readily make various modifications to these embodiments and apply the general principles described herein to other embodiments without requiring inventive effort. Therefore, the present invention is not limited to the above-described embodiments. Improvements and modifications made by those skilled in the art based on the disclosure of the present invention, without departing from the scope of the present invention, should be within the scope of protection of the present invention.

Claims

1. A theoretical simulation calculation method for oxygen reduction reaction based on first principles, characterized in that: The following steps are involved: S1. Preprocessing of disordered structures: a. Receive a cif file with an unordered structure and score placeholders; b. Expand the received cif file to generate an expanded cell structure; c. Randomly generate n ordered structures based on the expanded cell structure; d. Calculate the electrostatic energy of the system for each ordered structure; e. Screening to obtain several ordered structures with the lowest electrostatic energy; f. Perform DFT calculation and structural relaxation on the ordered structures obtained by screening to obtain the ordered structure with the lowest total energy; S2. Construction of slab model and generation of VASP input file: g. Based on the obtained ordered structure with the lowest total energy, a slab model of the material surface is constructed to simulate the oxygen reduction reaction; h. Using the slab model, use the Pymatgen library to generate the input file required for VASP calculation, which can be used for first-principles calculation; S3: Calculation of the energy barrier and overpotential of the oxygen reduction reaction: i. Using the generated VASP input file, calculate the energy barrier and overpotential of the oxygen reduction reaction using the computational hydrogen electrode method; j. calculating the free energy change for each reaction step of the oxygen reduction reaction to determine the overpotential; S4: Calculation of differential charge density: k. Based on the calculated structural information of the oxygen reduction reaction intermediates, perform electronic self-consistent calculations on each intermediate, slab model part, and adsorbate part to obtain a charge density file; 1. Using the charge density file, call VASPKit software to calculate the differential charge density and describe the change in charge distribution in the system to intuitively show the redistribution of charge during the oxygen reduction reaction.

2. The oxygen reduction reaction theoretical simulation calculation method based on first principles according to claim 1, characterized in that: In S1, the conditions for expanding the received cif file include: Ensure that the total number of each type of atom in the expanded unit cell is an integer.

3. The oxygen reduction reaction theoretical simulation calculation method based on first principles according to claim 1, characterized in that: In S2, the required input files include POSCAR, INCAR, KPOINTS, and POTCAR files.

4. The oxygen reduction reaction theoretical simulation calculation method based on first principles according to claim 1, characterized in that: In S3, the free energy-related parameters include: zero-point energy, change in total ground state energy, temperature, change in entropy, and electrode potential.

5. The oxygen reduction reaction theoretical simulation calculation method based on first principles according to claim 1, characterized in that: In step g to step l, the three reaction mechanisms are respectively carried out according to the four-electron process AEM mechanism, the four-electron process OPM mechanism, and the two-electron process.

6. The oxygen reduction reaction theoretical simulation calculation method based on first principles according to claim 5, characterized in that: in: The electron transfer process of the AEM mechanism is: *+O2+H + +e - →*OOH *OOH+H + +e - →*O+H2O *O+H + +e - →*OH *OH+H + +e - →*+H2O The electron transfer process of the OPM mechanism is: **+O2→*OO* *OO*+H + +e - →*OH*O *OH*O+H + +e - →*O*+H2O *O*+H + +e - →*OH *OH+H + +e - →**+H2O The electron transfer in a two-electron process is: *+O2+H + +e - →*OOH *OOH+H + +e - →*O+H2O2 *O, *OH, and *OOH are reaction intermediates adsorbed on the catalyst surface in the slab model.

7. The first-principles-based oxygen reduction reaction theoretical simulation calculation method according to claim 5, characterized in that: In S3, the free energy change of each reaction step is calculated using the following formula: ΔG=ΔZPE+ΔE-T×ΔS+ΔGU Where ΔZPE is the zero-point energy, ΔE is the change in total ground-state energy, T is the temperature, ΔS is the change in entropy, and ΔGU = eU, where U is the electrode potential. The zero-point energy and entropy of the intermediates are obtained by calculating the vibrational frequencies. The total energy and zero-point energy of each intermediate are calculated, and the overpotential is the largest of all reaction energy barriers.

8. The oxygen reduction reaction theoretical simulation calculation method based on first principles according to claim 1, characterized in that: In S4, the differential charge density is calculated based on the obtained charge density file, where the differential charge density Δρ is calculated by subtracting the charge density ρslab of the slab part and the charge density ρabsorbate of the adsorbate part from the charge density ρ of the system, that is, Δρ=ρ-ρslab-ρabsorbate.

9. A computer-readable storage medium having a computer program stored thereon, characterized in that: When the computer program is executed by a processor, the computer program implements the steps of the first-principles-based theoretical simulation calculation method for oxygen reduction reaction according to any one of claims 1 to 8.

10. A computer program product comprising a computer program, characterized in that When the computer program is executed by a processor, the computer program implements the steps of the first-principles-based theoretical simulation calculation method for oxygen reduction reaction according to any one of claims 1 to 8.

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