Xu Chuan was also a little surprised when he heard such a strange simulation situation.
The phenomenon of superconductivity sometimes works or fails. Although it is only a simulation test and not the final experimental result, some things can be seen.
In particular, material testing based on pure data simulation can eliminate some additional interference factors better than replicating experimental results, and is even purer and more representative to a certain extent.
"interesting."
After touching his chin and thinking for a moment, Xu Chuan muttered to himself and then looked up and said: "Package the entire simulation test data of the calculation model and send it to me. I will take a look."
With his mathematical ability and material ability, he might have a chance to find some situations from these data.
But to be honest, although he hopes that this KL-66 room temperature superconducting material will be a path that has never been discovered before, he does not have much hope.
Regardless of its synthesis route and materials, the name of KL-66 is called "modified lead apatite crystal structure", which is actually lead apatite doped with copper.
Although it requires a high temperature of more than 900 degrees to synthesize, there is no symbiosis of copper and lead apatite in nature, and a high temperature of more than 900 degrees is not difficult.
In the past billions of years of address activity, if this material really has superconductivity, then people will most likely be able to find it directly from nature.
However, science and technology have developed to this day. Not only all types of minerals on the earth have been discovered, but at least 99% of them have been explored, but this material has not been discovered.
Apart from this point, there is another key point that makes him aggravate his not very optimistic attitude to a certain extent.
The so-called 'modified lead apatite crystal structure KL-66', according to the two papers on arxiv, the core technology is to use CuCu2 to replace Pb22, inducing slight crystal structure distortion, thereby shrinking the volume by 0.48%.
This creates a superconducting quantum well at the interface between lead ions and phosphate, making the KL-66 material superconducting.
But based on his many years of experience in studying materials science, this substitution should not lead to superconductivity.
First of all, lead and copper atoms have very similar electronic structures. Replacing some lead atoms with copper atoms should not have a major impact on the electrical properties of the material.
Secondly, if he remembered correctly, although it is not impossible to use copper atoms to replace lead, theoretically speaking, the energy required to accomplish this goal is quite high in terms of thermodynamics.
The specific amount still needs to be calculated, but theoretically speaking, it is definitely not something that can be achieved by burning it at 900 degrees for more than ten hours.
...
After requesting a copy of KL-66 data and calculation model simulation data, Xu Chuan started calculations in his office.
Although there is no way to conclude that this KL-66 material is not a very-temperature superconductor through simple mathematical calculations, it can still be roughly calculated through atomic formation energy calculations, phonon spectra, tight binding models, etc.
【E5 \u003d Ef -[(No– 1)/No]* Ei.....】
[Set variable Cu equal to 3.615, unit metal dimension 3, boundary...]
[Calculate all pe/atoms in the project, calculate the sum of all reductions in the project c_eng...]
【Calculate the number of atoms......】
Based on the core data of the KL-66 paper and some data inferred from the computational model, Xu Chuan used the software of the Chuanhai Institute of Materials to rewrite the model.
This is one of the cores of computational materials science, and it is not difficult for him.
After spending some time, Xu Chuan put the reprocessed 'package' into the software and started running it.
After waiting for about ten minutes, the running results popped up.
Looking at the results of the calculation, Xu Chuan shook his head.
Judging from the calculation results of the formation energy, during the formation process of the KL-66 material, the energy required for copper atoms to replace lead requires a maximum of 16.3 MeV and a minimum of 12.6 MeV.
Even copper sulfide requires a minimum energy level of 8.7MeV.
This result is quite unfavorable for the synthesis of this KL-66 room temperature superconductor.
At a temperature of more than 900, it is completely impossible to heat the molecules inside the material to the order of 10Mev, which means that it is almost difficult for the copper in the KL-66 material to replace lead atoms.
According to South Korea, the core technology of KL-66 is to use CuCu2 instead of Pb22, which induces slight crystal structure distortion.
Then from the calculation of the formation energy, the first step is strangled.
Substitution is not possible, let alone distortion of the crystal structure.
Shaking his head, Xu Chuan did the calculation again. After confirming that the result was OK, he calculated the interaction Hamiltonian and phonon spectrum of the KL-66 material from scratch.
The calculation results of the phonon spectrum found that the virtual phonon mode exists in both the undoped and copper-doped structures of the KL-66 material, indicating that the structure is unstable and further confirms the results of the formation energy calculation.
As for the interaction Hamiltonian, in the KL-66 material, Cu will form a high-density flat region at the Fermi level. Quantum geometry shows that this region is a strongly localized state, which is not conducive to the formation of superconductivity and is more likely to lead to magnetism.
.
This chapter is not over yet, please click on the next page to continue reading! "Magnetism is a bit interesting. Is this thing a strong magnetic material?"
Staring at the calculated results, Xu Chuan thought for a moment.
It is not impossible that KL-66 is not a room temperature superconducting material, but a strong magnetic material.
On the contrary, judging from the calculation results of the three data items of formation energy, Hamiltonian, and phonon spectrum, the probability that it is a strong magnetic material is quite high.
Moreover, strong magnetic materials can also exhibit the characteristics of semi-magnetic levitation in the paper and the video posted by South Korea.
But I have to say that this incident has caused quite a heated discussion on the Internet.
When Xu Chuan was in class the next day, students asked about this matter during the daily question session after class.
"Professor, do you know the news about the KL-66 room temperature superconducting material that has been very popular in South Korea recently? Is this true? What do you think?"
Xu Chuan smiled and joked: "Me? Of course I sat and watched it."
Hearing this, the classroom burst into laughter.
Xu Chuan cleared his throat, coughed, and continued: "I do already know about the KL-66 room temperature superconducting material. However, I can't give a definite answer until the replica experiment comes out."
"If it is really a room-temperature superconductor, then for mankind, this is definitely one of the most glorious moments in history. The person who researched and invented this material will undoubtedly win the Nobel Prize."
"Material science will also usher in a great change as a result. Its synthesis method will prompt us to focus on materials synthesis in areas that were previously ignored and abandoned."
"It also means that in the field of materials before, we have undoubtedly taken many detours. Perhaps some materials with extremely high performance can be synthesized in a simpler way."
After hearing this, some students in the classroom immediately asked and shouted: "Professor, do you think it is successful?"
Hearing this question, Xu Chuan thought for a while and said: "If you had asked me this question yesterday, I would probably tell you that I don't know. After all, this kind of question usually needs to wait for the results of the replica experiment to come out.
Only then can I answer.”
"But today, I can actually talk to you."
Hearing this answer, the classroom immediately became excited, and many students even prepared their mobile phones and started recording videos.
Xu Chuan saw it but didn't pay much attention to it, and continued: "After learning about the KL-66 material two days ago, the Chuanhai Materials Research Institute under my name has already been conducting replica experiments."
"Out of interest, and because chemical material calculations are my area of expertise, I did some calculations based on some data provided in papers on arxiv."
"Through material calculations and simulations of the KL-66 material's formation energy, Hamiltonian, and phonon spectrum. Judging from the results, I am more inclined to believe that this material may be a strong magnetic material."
"The first is the calculation of the formation energy. Judging from the calculation results, in order for Cu atoms to replace the lead atoms in the KL-66 material, at least 10 Mev or more of energy is required..."
"...So overall, I am more inclined to think that it may be a strong magnetic material rather than a room temperature superconducting material."
"Of course, this is not a definite answer, just some speculation based on the experiments and calculations I have done."
"Currently, the Chuanhai Materials Research Institute under my name is following up on the replica experiments in this area. It is expected that the first to third batch of replica KL-66 materials will be released the day after tomorrow, and they will be tested by then.
To verify whether it has superconducting properties."
"As to whether KL-66 is a room-temperature superconducting material or something else, all this requires subsequent replication experiments to truly answer."
After a slight pause, he continued: "In addition, tomorrow I will sort out the calculation data I did, compile it into a paper and send it to Arxiv. If there are interested students, you can take a look."
"The above is very interesting about some of my original material calculation mathematics."
"I will also open a mathematics course on computational materials science later here, specifically teaching this aspect. Students who are interested can apply for it later."
.......
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