Construction method and application of alkali-activated silicon-aluminum material interface reaction model

Abstract

The invention discloses a construction method and application of an alkali-activated silicon-aluminum material interface reaction model. The construction method comprises the following steps: constructing a solid model; constructing a liquid model; combining the solid model with the liquid model to construct a solid-liquid reaction model; and carrying out molecular dynamics simulation on the solid-liquid reaction model to complete the construction of the alkali-activated silicon-aluminum material interface reaction model. The invention provides a molecular dynamics simulation method based on enhanced sampling, which is characterized in that a molecular dynamics simulation method is combined with an enhanced sampling technology, a ReaxFF potential function capable of describing diffusion behaviors and expressing intermolecular and intramolecular interaction is selected, and proper simulation processes and parameters are set; the interface interaction between the alkaline solution and the silicon-aluminum material can be explored from the atomic scale, so that a theoretical and technical foundation is laid for understanding the kinetics and reaction mechanism of early dissolution of the silicon-aluminum materials with different compositions in the alkaline solution.

Description

Technical Field

[0001] The present invention belongs to the technical field of molecular dynamics simulation, and in particular relates to a method for constructing an alkali-excited silicon-aluminum material interface reaction model and its application. Background Art

[0002] In recent years, excessive emissions of greenhouse gases such as carbon dioxide have led to serious global environmental problems. The energy and industrial sectors are the main sources of carbon emissions, especially the construction and cement industries. Therefore, there is an urgent need to seek greener and more environmentally friendly production technologies and low-carbon cementitious systems.

[0003] Alkali-activated cementitious materials are green, low-carbon cementitious materials made by reacting amorphous aluminosilicate solid waste materials with volcanic ash or potential hydraulic properties with an alkali activator. These materials feature low energy consumption, high strength, and excellent durability, and are highly valued for their waste utilization, energy conservation, and carbon reduction. Industrial solid wastes such as fly ash, coal gangue, boiling furnace slag, coal cinder, and silica fume contain relatively high amounts of amorphous or metastable SiO2 and Al2O3, or small amounts of CaO. Similar to volcanic ash, these materials are difficult to gel on their own. However, their active SiO2 and Al2O3 can be activated by alkalis such as NaOH or alkali metal salts, producing a certain degree of hydraulic hardness. These materials can replace or partially replace cement clinker in construction applications, while also facilitating the consumption of excess industrial solid waste.

[0004] However, solid waste raw materials come from a wide range of sources and their composition fluctuates significantly. This results in significant differences in the products formed when different raw materials react with alkaline activators, resulting in varying mechanical properties. Experimental studies have shown that when the Al / Si ratio increases from 0.26 to 0.33 and the Na2O / Al2O3 ratio is approximately 1, the gel strength performance is excellent. Exceeding this range results in reduced system strength. This nonlinear relationship highlights the importance of understanding the mechanism underlying the Al / Si ratio-structure-property correlation.

[0005] Although the alkali-induced reaction theory of "depolymerization-condensation" has been formed and experimental research data have continuously promoted the development of this theory, there are still technical bottlenecks in the study of the microscopic mechanism of the early alkali-induced reaction, such as: (1) Traditional characterization methods such as XRD, 29 Si NMR can only obtain static structural information, but cannot analyze the nanosecond interface reaction dynamics and the reaction details at the atomic / molecular scale. For example, some studies have observed that increasing the nominal Si / Al ratio of the sample will lead to the product 29 The Si MAS NMR resonance spectrum shifts to lower frequencies, and the resonance becomes increasingly asymmetric. However, it is still difficult to understand the regulatory mechanism of the Al / Si ratio on the bond rupture path. (2) Cross-scale correlation fracture: There is a lack of quantitative correlation models between macroscopic mechanical tests (such as compressive strength) and atomic-scale bonding behavior, resulting in material design relying on trial-and-error methods.

[0006] Molecular dynamics (MD) simulation provides a new way to break through the above bottleneck, but how to construct relevant molecular dynamics models to achieve better simulation effects so that base-excited reactions can be observed on a shorter time scale and a smaller atomic scale remains a challenging problem. Summary of the Invention

[0007] In order to overcome at least one of the problems existing in the above-mentioned prior art, one of the objectives of the present invention is to provide a method for constructing an alkali-activated silicon-aluminum material interface reaction model.

[0008] A second object of the present invention is to provide a method for analyzing the interfacial reaction activity of alkali-activated silicon-aluminum materials.

[0009] In order to achieve the above object, the technical solution adopted by the present invention is:

[0010] A first aspect of the present invention provides a method for constructing an alkali-activated silicon-aluminum material interface reaction activity, comprising the following steps:

[0011] Constructing a solid model, wherein the solid model is an amorphous silicon-aluminum material solid model; the step of constructing the solid model includes amorphization treatment; the amorphization treatment method is selected from the replica exchange molecular dynamics method; the replica temperature range of the replica exchange molecular dynamics method is 300-600K, and the replica exchange frequency is 50-150ps -1 ;

[0012] Constructing a liquid model, wherein the liquid model is an alkaline solution model;

[0013] combining the solid model and the liquid model to construct a solid-liquid reaction model;

[0014] The solid-liquid reaction model is subjected to molecular dynamics simulation to complete the construction of the alkali-excited silicon-aluminum material interface reaction model; the force field used in the molecular dynamics simulation is the ReaxFF force field.

[0015] The method of the present invention can improve the sampling efficiency of phase space compared to traditional molecular dynamics (MD) method, so that the reaction is closer to the real reaction system, and has higher accuracy from the perspective of fitting the actual reaction. In addition, the present invention considers the ease of describing the solid-liquid interface reaction mechanism, adopts ReaxFF reaction force field, although the simulation accuracy is sacrificed compared to the first principles (DFT calculation), the simulation efficiency is higher, and it can be applied to a simulation system with a larger model and more atoms; and compared to the Monte Carlo (GCMC) simulation method, the simulation of a larger model system is sacrificed, but the reaction accuracy is improved, the bonding and breaking of the solid-liquid interface reaction can be observed, and the chemical reaction of the silicon-aluminum material under the excitation of the alkaline solution and the structural change of the solid-liquid interface can be better explained.

[0016] In addition, the actual alkali excitation reaction temperature is between room temperature and about 60°C. Properly increasing the temperature is beneficial to increasing the sampling of the reaction. The present invention adopts a suitable replica temperature to save computing resources and obtain better sampling effects; and a suitable exchange frequency is beneficial to ensuring the system's traversability, sampling efficiency and computing stability.

[0017] The exchange frequency has an important impact on the sampling efficiency and accuracy of the simulation. The exchange frequency is determined by the set simulation time step (such as 0.1fs) and the number of steps at which exchanges occur (such as once every 100 steps). If the exchange frequency is set improperly, it may affect the system's ergodicity, sampling efficiency, and computational stability. If the exchange frequency is too high (too few steps, too frequent exchanges), replicas switch frequently between different temperatures, and the system may not have enough time to fully equilibrate at one temperature; this may lead to discontinuous energy distribution and a decrease in the Metropolis acceptance rate. If the exchange frequency is too low, the replica stays at a certain temperature for a long time, resulting in insufficient state exchange between different temperatures; this may lead to insufficient ensemble sampling, especially in systems with more complex free energy surfaces; it may also affect the accuracy of the free energy calculation, making it difficult for high-temperature replicas to help low-temperature replicas overcome potential barriers.

[0018] In some embodiments of the present invention, the running time of the amorphization process is 15 to 25 ps; for example, it can be any value among 15 ps, 18 ps, 20 ps, ​​22 ps or 25 ps, or a range of values ​​therebetween.

[0019] The present invention improves the phase space sampling efficiency through a specific replica exchange molecular dynamics method (REMD), quickly completes the amorphization of the crystal, and shortens the required amorphization processing time.

[0020] In some embodiments of the present invention, the amorphization treatment includes the steps of constructing β-SiO2 crystals, cell expansion treatment and Al substitution in sequence.

[0021] In some embodiments of the present invention, the unit cell parameters of the β-SiO2 crystal are α=β=90°, γ=120°, and the space group is P63 / mmc.

[0022] In some embodiments of the present invention, the cell expansion process obtains a supercell, in which the a-axis is expanded to 7 to 9 times the a-axis of the original unit cell, the b-axis is expanded to 7 to 9 times the b-axis of the original unit cell, and the c-axis is expanded to 3 to 5 times the c-axis of the original unit cell; in some specific embodiments of the present invention, in the supercell, the a-axis is expanded to 8 times the a-axis of the original unit cell, the b-axis is expanded to 8 times the b-axis of the original unit cell, and the c-axis is expanded to 4 times the c-axis of the original unit cell (i.e., an 8×8×4 supercell is obtained).

[0023] Using an appropriate degree of cell expansion can help reduce fluctuations in parameters such as energy, and reduce the amount of calculation and time consumed.

[0024] In some embodiments of the present invention, the supercell contains 750 to 800 Si atoms, for example, 750, 760, 770, 780, 790, or 800, or any range therebetween. In some specific embodiments of the present invention, the supercell contains 768 Si atoms.

[0025] In some embodiments of the present invention, the Al substitution is to replace Si atoms with Al atoms to obtain unit cells with different aluminum-silicon ratios. By adjusting the ratio of Al substitution, unit cells with different aluminum-silicon ratios can be obtained, thereby exploring the effect of the aluminum-silicon ratio on interfacial reactivity.

[0026] In some embodiments of the present invention, the number of replicas of the replica exchange molecular dynamics method is 6 to 10; in some embodiments of the present invention, the number of replicas of the replica exchange molecular dynamics method is 8.

[0027] In some embodiments of the present invention, the replica temperature range of the replica exchange molecular dynamics method is 250-550K; in some specific embodiments of the present invention, the replica temperature range of the replica exchange molecular dynamics method is 300-508.93K.

[0028] In some embodiments of the present invention, the temperatures of the replicas in the replica exchange molecular dynamics method are distributed according to a geometric series or exponential spacing. Because the free energy of a physical system typically exhibits a nonlinear relationship with temperature, using a geometric series or exponential spacing distribution, compared to an evenly spaced temperature distribution, helps ensure uniform exchange probabilities between high and low temperature regions.

[0029] In some specific embodiments of the present invention, the number of replicas of the replica exchange molecular dynamics method is 8, and the temperatures of the 8 replicas are 300.00K, 321.37K, 344.02K, 367.88K, 393.07K, 419.70K, 462.43K, and 508.93K, respectively.

[0030] In some embodiments of the present invention, the replica exchange frequency of the replica exchange molecular dynamics method is 80 to 120 ps. -1 In some embodiments of the present invention, the replica exchange frequency of the replica exchange molecular dynamics method is 100 ps -1 .

[0031] In some embodiments of the present invention, the alkaline solution model includes Na + OH - and H2O.

[0032] In some embodiments of the present invention, the steps of constructing the alkaline solution model include: using the MaterialsStudio module to construct the Na + OH - and H2O, and then applied the Materials Studio Amorphous Cell module to convert Na + OH - and H2O are randomly placed into the box to construct a solution box, and relaxation is performed for 5 to 20 ps (such as 10 ps) under the NPT ensemble. Further, Berendsen pressure control and isotropic compression are adopted.

[0033] In some embodiments of the present invention, the size of the alkaline solution model is In some embodiments of the present invention, the size of the alkaline solution model is

[0034] In some embodiments of the present invention, the water molecule density of the alkaline solution model is 0.995-1.00 g / cm 3 In some embodiments of the present invention, the water molecule density of the alkaline solution model is 0.997 g / cm 3 .

[0035] Using an appropriate water molecule density is helpful in making the simulated environment as close as possible to the real solution environment.

[0036] In some embodiments of the present invention, the step of combining the solid model with the liquid model includes: inserting the solid model along the Z-axis direction (like ) vacuum layer to prevent the initial atoms from overlapping, and the liquid model is combined to obtain the solid-liquid reaction model. Further, the conjugate gradient (CG) algorithm is used for energy minimization, and the convergence criterion is 10 -7 ~10 -5 kcal / mol (such as 10 -6 kcal / mol).

[0037] In some embodiments of the present invention, the size of the solid-liquid reaction model is In some embodiments of the present invention, the size of the solid-liquid reaction model is

[0038] In some embodiments of the present invention, the conditions adopted for the molecular dynamics simulation include: maintaining a constant temperature of 300K using the Nose-Hoover method, with a relaxation time of 0.05 to 0.2ps; running for 40 to 60ps under the NVT ensemble, with a time step of 0.1fs and a trajectory output frequency of 10fs; in some specific embodiments of the present invention, the conditions adopted for the molecular dynamics simulation include: maintaining a constant temperature of 300K using the Nose-Hoover method, with a relaxation time of 0.1ps; running for 50ps under the NVT ensemble, with a time step of 0.1fs and a trajectory output frequency of 10fs.

[0039] In some embodiments of the present invention, the parameter set of the ReaxFF force field is selected from HOSiAlNa-2015.

[0040] In some embodiments of the present invention, the method for constructing the alkali-activated silicon-aluminum material interface reaction model is performed in LAMMPS software.

[0041] The second aspect of the present invention provides an analysis method for the interfacial reaction activity of alkali-excited silicon-aluminum materials, comprising the following steps: obtaining an interfacial reaction model of alkali-excited silicon-aluminum materials according to the construction method described in the first aspect of the present invention, obtaining the interfacial reaction activity of alkali-excited silicon-aluminum materials under different construction parameters, and thereby analyzing the influencing factors of the interfacial reaction activity of alkali-excited silicon-aluminum materials.

[0042] In some embodiments of the present invention, the evaluation index of the alkali-activated silica-alumina material interface reaction activity includes the structural parameters and / or kinetic parameters of the alkali-activated silica-alumina material interface reaction model.

[0043] In some embodiments of the present invention, the structural parameters include at least one of bond length distribution, bond angle distribution, RDF distribution or Qn distribution.

[0044] In some embodiments of the invention, the kinetic parameter comprises mean square displacement (MSD), time correlation function (TCF), or a combination thereof.

[0045] In some embodiments of the present invention, the construction parameters include the aluminum-silicon ratio of the amorphous silicon-alumina material solid model.

[0046] In some embodiments of the present invention, the aluminum-silicon ratio of the amorphous silicon-aluminum material solid model is 0.1 to 0.5; in some embodiments of the present invention, the aluminum-silicon ratio of the amorphous silicon-aluminum material solid model is 0.1 to 0.4; for example, it can be any value among 0.1, 0.2, 0.3 or 0.4 or a range value between any two of them.

[0047] The beneficial effect of the present invention is: the present invention provides a molecular dynamics simulation method based on enhanced sampling, which uses a molecular dynamics simulation method combined with enhanced sampling technology, selects a ReaxFF potential function that can describe diffusion behavior and express intermolecular and intramolecular interactions, and sets appropriate simulation processes and parameters, which is conducive to exploring the interfacial interaction between alkaline solutions and silicon-aluminum materials at the atomic scale, thereby laying a theoretical and technical foundation for understanding the kinetics and reaction mechanism of early dissolution of silicon-aluminum materials of different compositions in alkaline solutions.

[0048] Specifically, compared with the prior art, the present invention has the following advantages:

[0049] 1. The alkali-activated silica-alumina material interface reaction model constructed in the present invention can be used to analyze the influence of different construction parameters on the alkali-activated silica-alumina material interface reaction activity, especially the influence of different aluminum-silicon ratios on the silica-alumina material chain structure, reveal the interaction between silica-alumina materials with different aluminum-silicon ratios and alkaline solutions at the reaction interface, and evaluate the alkali-activated reaction activity of silica-alumina materials with different aluminum-silicon ratios.

[0050] 2. The interfacial reaction model of the present invention can be combined with atomic-scale dynamic bonding analysis to reveal the influence of the Al / Si ratio on early dissolution kinetics through multi-parameter correlation analysis, thereby providing theoretical guidance for the design of alkali-activated cementitious materials. BRIEF DESCRIPTION OF THE DRAWINGS

[0051] Figure 1 Schematic diagram of the process of analyzing the interfacial reaction activity of alkali-activated silicon-aluminum materials in an embodiment of the present invention.

[0052] Figure 2 Schematic diagram of the structure of the amorphous silicon-aluminum material solid model in Example 1 of the present invention.

[0053] Figure 3 Schematic diagram of the structure of the NaOH liquid model in Example 1 of the present invention.

[0054] Figure 4 Schematic diagram of the structure of the solid-liquid reaction model in Example 1 of the present invention.

[0055] Figure 5 This is the atomic structure distribution diagram of the solid-liquid reaction interface in Example 1 of the present invention.

[0056] Figure 6 This is a diagram showing the bond length distribution changes during the Brief-PT simulation of the Al / Si=0.2 system in Example 1 of the present invention.

[0057] Figure 7 This is a diagram showing the change in O-Si-O bond angle distribution during the Brief-PT simulation of the Al / Si=0.2 system in Example 1 of the present invention.

[0058] Figure 8 Graph showing the Qn distribution changes of Si atoms during the Brief-PT simulation of systems with different Al / Si ratios in Examples 1 to 4 of the present invention.

[0059] Figure 9 The solid-liquid interface bond length distribution diagram of different Al / Si ratio systems in Examples 1 to 4.

[0060] Figure 10 Graphs showing the Si-O-Si bond angle distribution at the solid-liquid interface for different Al / Si ratio systems in Examples 1 to 4.

[0061] Figure 11 These are the MSD curves of interface atoms in systems with different Al / Si ratios in Examples 1 to 4.

[0062] Figure 12 These are the TCF curves of interface atoms in systems with different Al / Si ratios in Examples 1 to 4. DETAILED DESCRIPTION

[0063] The content of the present invention is further described in detail below through specific examples. It should be understood that the following examples are only used to further illustrate the present invention and cannot be interpreted as limiting the scope of protection of the present invention. Some non-essential improvements and adjustments made by those skilled in the art based on the principles set forth in the present invention all fall within the scope of protection of the present invention. The specific process parameters and the like in the following examples are only examples within a suitable range, and those skilled in the art can make selections within a suitable range through the description herein, and are not limited to the specific data exemplified below. The raw materials, reagents or devices used in the following examples and comparative examples, unless otherwise specified, can be obtained from conventional commercial sources, or can be obtained by existing known methods.

[0064] The embodiment of the present invention provides a method for constructing an alkali-activated silicon-aluminum material interface reaction model, and on this basis provides a method for analyzing the activity of the alkali-activated silicon-aluminum material interface reaction. The flow diagram of the analysis method is as follows: Figure 1 This analytical method can be used to analyze the effects of different aluminum-silicon ratios on the chain structure of silicon-aluminum materials, intuitively demonstrate the interaction between silicon-aluminum materials with different aluminum-silicon ratios and alkaline solutions at the reaction interface, and evaluate the alkaline-induced reaction activity of silicon-aluminum materials with different aluminum-silicon ratios.

[0065] In the embodiment of the present invention, the evaluation index of the alkali-activated silicon-aluminum material interface reaction activity includes the structural parameters and kinetic parameters of the alkali-activated silicon-aluminum material interface reaction model, wherein:

[0066] (1) Structural parameters include:

[0067] 1. RDF distribution: Captures the bond strength and distance between surface atoms to study the structural properties of materials at different distances.

[0068] 2. Bond length and angle distribution (Si-O bond length: Al-O bond length: ): Statistically analyze the distribution of bond lengths and bond angles between specific types of atoms in a system to understand the stability, geometry, and changes of structural units in the material.

[0069] 3. Qn distribution (calculated using Cutoff method, Si-O: Al-O: ): Characterize the polymer structure of the material, such as chain, ring, three-dimensional network and other structural forms, and then evaluate the solubility and chemical stability of the material.

[0070] (2) Kinetic parameters:

[0071] 1. Mean Square Displacement (MSD) MSD analysis: Calculate the mean square displacement of atoms or molecules over time to evaluate their diffusion characteristics. The mean square displacement is defined by the following formula:

[0072]

[0073] In the above formula, N is the number of particles, t represents time, is the vector distance traveled by a given particle in a period of time, and the symbol “<…>” represents the ensemble average after equilibrium.

[0074] 2. Time Correlation Function (TCF) Analysis: Quantitatively describes the strength and stability of various chemical bonds formed between molecules, between ions, and between ions and molecules. It is calculated using the following formula:

[0075]

[0076] In the above formula, t represents time; δb(t) is a binary operator, which means that if the atomic pair forms a bond at time t, the value is equal to 1, otherwise it is equal to 0; δb(0) is a binary operator, which means that if the atomic pair forms a bond at the initial time (t = 0), the value is equal to 1, otherwise it is equal to 0; the symbol "<...>" represents the average of the entire ensemble.

[0077] In the following examples, "Oaq" represents an oxygen atom in a liquid model.

[0078] Example 1

[0079] A method for constructing an alkali-activated silicon-aluminum interface reaction model (Al / Si=0.2 system, all simulations are performed in LAMMPS software), the specific steps are as follows:

[0080] (1) Solid model construction

[0081] a. Initial model: β-SiO2 crystal (space group P63 / mmc, unit cell parameters α=β=90°, γ=120°);

[0082] b. Cell expansion: construct an 8×8×4 supercell (containing 768 Si atoms);

[0083] c. Al substitution: Si atoms were randomly replaced with Al atoms according to Al / Si = 0.2, with a total of 154 Si atoms replaced with Al.

[0084] d. Amorphization treatment: Replica exchange molecular dynamics (REMD) was used, with 8 replicas set at 300.00K, 321.37K, 344.02K, 367.88K, 393.07K, 419.70K, 462.43K, and 508.93K, and an exchange frequency of 100ps. -1 By setting more frequent interruptions so that the low-temperature state periodically repopulates the simulation set, this method is defined as Brief-PT and runs for 20 ps to obtain an amorphous structure.

[0085] Figure 2 Schematic diagram of the structure of the solid model of amorphous silicon-aluminum material in this example; (a) is the solid model after Al substitution; (b) is the solid model after amorphization treatment; in the figure, silicon atoms are pink, aluminum atoms are yellow, and oxygen atoms are blue-purple.

[0086] (2) Liquid model construction

[0087] a. Composition: NaOH solution (concentration 1.31 mol / L), water molecule density 0.997 g / cm 3 ;

[0088] b. Modeling: Use Materials Studio module to build Na + OH - and H2O, and then use the MaterialsStudio Amorphous Cell module to convert Na + OH - and H2O are randomly placed in the box, with a build size of Solution box;

[0089] c. Relaxation: 10 ps relaxation was performed under the NPT ensemble (Berendsen pressure control, isotropic compression).

[0090] Figure 3 This is a schematic diagram of the structure of the NaOH liquid model in this example. In the figure, sodium atoms are rose red, oxygen atoms are green, and hydrogen atoms are light green.

[0091] (3) Interface system construction

[0092] a. Vacuum layer setting: insert along the Z-axis direction of the solid model The vacuum layer prevents the initial atoms from overlapping;

[0093] b. Solid-liquid reaction model: The liquid model is combined with the solid model after inserting the vacuum layer to obtain the solid-liquid reaction model. The conjugate gradient (CG) algorithm is used for energy minimization with a convergence criterion of 10 -6 kcal / mol. Final model size Contains approximately 4884 atoms.

[0094] Figure 4 Schematic diagram of the structure of the solid-liquid reaction model in this example; (a) is when the solid model and the liquid model are just combined, that is, t = 0ps; (b) is when the solid model and the liquid model are combined for 50ps, that is, t = 50ps; in the figure, silicon atoms are pink, aluminum atoms are yellow, oxygen atoms in the solid model are blue-purple, sodium atoms are rose-red, oxygen atoms in the liquid model are green, and hydrogen atoms are light green. Figure 5 This is the atomic structure distribution diagram of the solid-liquid reaction interface in this example.

[0095] (4) Molecular dynamics simulation

[0096] The ReaxFF force field (parameter set: HOSiAlNa-2015) was used, the Nose-Hoover method was used to control the temperature at 300K, the relaxation time was 0.1ps, the NVT ensemble was run for 50ps, the time step was 0.1fs, and the trajectory output frequency was 10fs to complete the construction of the alkali-excited silicon-aluminum material interface reaction model.

[0097] For the alkali-activated silicon-aluminum material interface reaction model of Example 1, the Python code is edited to count parameters such as RDF, bond length and angle, Qn distribution, MSD, TCF, etc. The Python analysis code is programmed according to the definition and calculation formula of these data, and the relationship between these parameters and the structural parameter r or time is calculated and visualized.

[0098] The simulation results are as follows Figures 6-7 shown. Figure 6 This is a diagram showing the bond length distribution changes during the Brief-PT simulation of the Al / Si=0.2 system in Example 1; wherein (a) is the Si-O bond length; and (b) is the Al-O bond length. Figure 7 This is a diagram showing the change in O-Si-O bond angle distribution during the Brief-PT simulation of the Al / Si=0.2 system in Example 1.

[0099] Some simulated data are as follows:

[0100] (1) Main peak of Si-O bond length Al-O bond length main peak The main peak of the O-Si-O bond angle is 108±1.5°. (2)Q 3 / Q 4 =1.5. (3) The TCF decay time of Al-Oaq is τ = 11 ps, indicating a relatively high bond breaking frequency.

[0101] Example 2

[0102] A method for constructing an alkali-activated silicon-aluminum material interface reaction model is different from Example 1 in that, in step (1) c, the number of Al replacements is adjusted, and a total of 230 Si are replaced with Al, so that Al / Si of the solid model is 0.3; the other steps are the same as Example 1.

[0103] Some simulation data are as follows: (1) Q 3 / Q 4 =1.38. (2) TCF decay time τ of Al-Oaq = 13 ps.

[0104] Example 3

[0105] A method for constructing an alkali-activated silicon-aluminum material interface reaction model is different from Example 1 in that the number of Al replacements is adjusted in step (1) c so that Al / Si of the solid model is 0.1; the other steps are the same as Example 1.

[0106] Example 4

[0107] A method for constructing an alkali-activated silicon-aluminum material interface reaction model is different from Example 1 in that the number of Al replacements is adjusted in step (1) c so that Al / Si of the solid model is 0.4; the other steps are the same as Example 1.

[0108] Figure 8 Graphs showing the Qn distribution changes of Si atoms during the Brief-PT simulation of different Al / Si ratio systems in Examples 1 to 4, where (a) is Al / Si = 0.1; (b) is Al / Si = 0.2; (c) is Al / Si = 0.3; and (d) is Al / Si = 0.4. Figure 9 The solid-liquid interface bond length distribution diagram of different Al / Si ratio systems in Examples 1 to 4; among them, (a) is the Si-O bond length; (b) is the Al-O bond length, and the running time is 45ps. Figure 10 The Si-O-Si bond angle distribution diagram of the solid-liquid interface of different Al / Si ratio systems in Examples 1 to 4, the running time is 45ps. Figure 11 1 and 2 are the MSD curves of interface atoms in systems with different Al / Si ratios in Examples 1 to 4; wherein (a) is Oaq; and (b) is H. Figure 12 These are the TCF curves of interface atoms in systems with different Al / Si ratios in Examples 1 to 4; (a) is Si-Oaq; (b) is Al-Oaq.

[0109] Analysis of the simulation results of Examples 1 to 4 shows that:

[0110] (1) Qn: As the Al / Si ratio increases, the Q of the solid system after amorphization 3 / Q 4 The ratio first decreases and then increases.

[0111] (2) Bond length and bond angle: With the increase of Al / Si ratio, the Si-O bond and Al-O bond at the solid-liquid interface shift to the left, and the Si-O-Si bond angle shifts to the right, which shows an increasing trend, indicating that the solid reaction is more intense.

[0112] (3) Mean square displacement (MSD) of atoms: With the increase of Al / Si ratio, the mean square displacement of Qaq and H atoms both show an increasing trend, indicating that the solid-liquid reaction is more intense at high Al / Si ratio.

[0113] (4) Time correlation function (TCF): With the increase of Al / Si ratio, the TCF value of Si-O bond shows a decreasing trend, which indicates that the presence of Al enhances the reactivity of silicon-aluminum materials; the TCF decay time of Al-Oaq is τ = 3 ~ 15ps, showing a higher bond breaking frequency. With the increase of Al / Si ratio, the decay time is prolonged, indicating that the bonding between Al atoms and solution O atoms is more stable at high Al / Si ratio.

[0114] The REMD method employed in the present invention exchanges replicas between multiple temperatures, allowing low-temperature replicas to briefly acquire higher energy at high temperatures, thereby overcoming potential barriers and improving sampling efficiency. After acquiring sufficient energy in the high-temperature region, the low-temperature replica can return to the low-temperature region, accelerating the structural transformation process and helping the system more comprehensively sample the potential energy surface. Data from the Qn diagram of the REMD method in the present invention show that the distributions of Si atoms Q0, Q1, Q2, Q3, and Q4 are 0%, 6%, 28%, 40%, and 26%, respectively, and the time to reach equilibrium from crystalline to amorphous is within 20 ps.

[0115] In contrast, traditional MD methods use a single temperature for simulation, and the system's exploration capabilities rely on the randomness of thermal motion. At low temperatures, the system's energy fluctuations are small, making it easy to fall into local minimum potential energy wells, resulting in low sampling efficiency. The time step calculated by traditional MD methods is usually 1 fs or less, requiring a long simulation run. Generally, simulation times of up to tens of ns are set. Compared with traditional MD methods, the method in the embodiment of the present invention has a faster simulation speed, which can be accelerated by at least 2 orders of magnitude.

[0116] The alkali-activated silica-alumina interface reaction model constructed in the embodiments of the present invention can be used to analyze the effects of different construction parameters on the alkali-activated silica-alumina interface reaction activity, particularly the effects of different aluminum-silicon ratios on the chain structure of silica-alumina materials, reveal the interaction between silica-alumina materials with different aluminum-silicon ratios and alkaline solutions at the reaction interface, and evaluate the alkali-activated reaction activity of silica-alumina materials with different aluminum-silicon ratios. Furthermore, the interface reaction model in the embodiments of the present invention can be combined with atomic-scale dynamic bonding analysis to reveal the influence of the Al / Si ratio on early dissolution kinetics through multi-parameter correlation analysis, thereby providing theoretical guidance for the design of alkali-activated cementitious materials.

[0117] In summary, the present invention provides a molecular dynamics simulation method based on enhanced sampling. This method uses a molecular dynamics simulation method combined with enhanced sampling technology, selects the ReaxFF potential function that can describe the diffusion behavior and express the intermolecular and intramolecular interactions, and sets appropriate simulation processes and parameters. It is beneficial to explore the interfacial interaction between alkaline solutions and silicon-aluminum materials at the atomic scale, thereby laying a theoretical and technical foundation for understanding the kinetics and reaction mechanism of early dissolution of silicon-aluminum materials of different compositions in alkaline solutions.

Claims

1. A method for constructing an alkali-activated silicon-aluminum material interface reaction model, characterized in that: The following steps are involved: Constructing a solid model, wherein the solid model is an amorphous silicon-aluminum material solid model; the step of constructing the solid model includes amorphization treatment; the amorphization treatment method is selected from the replica exchange molecular dynamics method; the replica temperature range of the replica exchange molecular dynamics method is 300-600K, and the replica exchange frequency is 50-150ps -1 ; Constructing a liquid model, wherein the liquid model is an alkaline solution model; combining the solid model and the liquid model to construct a solid-liquid reaction model; Performing molecular dynamics simulation on the solid-liquid reaction model to complete the construction of an alkali-excited silicon-aluminum material interface reaction model; The force field used in the molecular dynamics simulation is the ReaxFF force field.

2. The construction method according to claim 1, characterized in that The running time of the amorphization process is 15 to 25 ps.

3. The construction method according to claim 1, characterized in that The amorphization process includes the steps of constructing β-type SiO2 crystals, cell expansion and Al substitution in sequence.

4. The construction method according to claim 3, characterized in that The unit cell parameters of the β-SiO2 crystal are α=β=90°,γ=120°,space group is P63 / mmc; And / or, the cell expansion process obtains a supercell, in which the a-axis of the supercell is expanded to 7 to 9 times the a-axis of the original cell, the b-axis is expanded to 7 to 9 times the b-axis of the original cell, and the c-axis is expanded to 3 to 5 times the c-axis of the original cell; And / or, the Al substitution is to replace Si atoms with Al atoms to obtain unit cells with different aluminum-silicon ratios.

5. The construction method according to claim 1, characterized in that The number of replicas in the replica exchange molecular dynamics method is 6 to 10; And / or, the temperatures of each replica of the replica exchange molecular dynamics method are distributed according to a geometric series.

6. The construction method according to claim 1, characterized in that The size of the alkaline solution model is And / or, the size of the solid-liquid reaction model is 7. The construction method according to claim 1, characterized in that The conditions adopted in the molecular dynamics simulation include: The Nose-Hoover was kept at a constant temperature of 300 K and a relaxation time of 0.05 to 0.2 ps. The NVT ensemble was run for 40 to 60 ps with a time step of 0.1 fs and a trajectory output frequency of 10 fs.

8. A method for analyzing the interfacial reaction activity of alkali-activated silicon-aluminum materials, characterized in that: The following steps are involved: According to the construction method described in any one of claims 1 to 7, an alkali-activated silicon-aluminum material interface reaction model is obtained, and the alkali-activated silicon-aluminum material interface reaction activity under different construction parameters is obtained, thereby analyzing the influencing factors of the alkali-activated silicon-aluminum material interface reaction activity.

9. The analysis method according to claim 8, characterized in that The evaluation index of the alkali-activated silica-alumina material interface reaction activity includes the structural parameters and / or kinetic parameters of the alkali-activated silica-alumina material interface reaction model; the structural parameters include at least one of bond length distribution, bond angle distribution, RDF distribution or Qn distribution; the kinetic parameters include mean square displacement, time correlation function or a combination thereof; And / or, the construction parameters include the aluminum-silicon ratio of the amorphous silicon-aluminum material solid model.

10. The analysis method according to claim 8, characterized in that The aluminum-silicon ratio of the amorphous silicon-aluminum material solid model is 0.1-0.5.

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