Chapter 441: Exit Early

Hearing such a strange simulation, Xu Chuan was also a little surprised.

The superconductivity phenomenon sometimes works and sometimes doesn't. Although it is just a simulation test, not the final experimental result, it can also see something.

Especially the material test of pure data simulation, compared with the replica experimental results, it can eliminate some additional interference factors, and it is even purer and more representative to some extent.

"It's interesting."

Touching his chin and thinking for a while, Xu Chuan muttered to himself and looked up and said: "Package the simulation test data of the calculation model and send it to me. I'll take a look."

With his mathematical ability and material ability, there may be a chance to find some situations from these data.

But to be honest, for this KL-66 room temperature superconducting material, although he hopes that this is a road that has never been discovered, he does not have much hope.

Apart from 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 takes more than 900 degrees Celsius to synthesize, there are copper and lead apatite coexisting minerals in nature, and more than 900 degrees Celsius is not difficult.

In the past billions of years of address activities, if this material really has superconductivity, then people are likely to find it directly from nature.

But with the development of science and technology, all kinds of minerals on the earth, not to mention all kinds have been discovered, at least more than 99% of the minerals have been explored, but this material has not been found.

Apart from this point, there is another key point that also makes him a little more optimistic.

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+, induce a tiny crystal structure distortion, so that the volume shrinks by 0.48%, thereby constructing a superconducting quantum well at the interface between lead ions and phosphates, and making this KL-66 material superconducting.

But based on his own years of experience in researching materials science, this substitution should not be able to form superconductivity.

First, lead and copper atoms have very similar electronic structures, and replacing some lead atoms with copper atoms should not have a significant impact on the electrical properties of the material.

Secondly, if he remembers correctly, it is not impossible to use copper atoms to replace lead, but theoretically, the energy required to achieve this goal is quite high in thermodynamics.

The specific amount still needs to be calculated, but theoretically, it is definitely not something that can be achieved by burning at 900 degrees for more than ten hours.

After asking for a copy of KL-66 data and calculation model simulation data, Xu Chuan started the calculation in his office.

Although there is no way to determine that this KL-66 material is not a very-low-temperature superconductor through simple mathematical calculations, it can still be roughly deduced through atomic formation energy calculations, phonon spectra, tight binding models, etc.

【E5 = Ef -[(No– 1)/No]* Ei】

【Set variable Cu equal to 3.615, unit metal dimension 3, boundary.】

【Calculate all engineering pe/atom, calculate all engineering reduction sum c_eng】

【Calculate the number of atoms.】

Comparing the core data of the KL-66 paper and some data inferred by the calculation model, Xu Chuan used the software of the Chuanhai Materials Research Institute 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 more than ten minutes, the running results popped up.

【Cupb(Cu):△Ef(eV)Max=16.3Mev、△Ef(eV)Min=12.6Mev】

【Cupb(Cu3P):△Ef(eV)Max=16.1Mev、△Ef(eV)Min=12.1Mev】

【Cupb(CuS)1】

Looking at the calculated results, Xu Chuan shook his head.

According to the formation energy calculation results, in the formation process of KL-66 material, the energy required for copper atoms to replace lead is 16.3Mev at most and 12.6MeV at least.

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 impossible to heat the molecules inside the material to the order of 10Mev, which means that it is almost difficult for copper in KL-66 material to replace lead atoms.

According to South Korea, the core technology of KL-66 is to use CuCu2+ to replace Pb22+, which induces a slight crystal structure distortion.

Then from the calculation of formation energy, the first step is strangled.

Even substitution cannot be done, let alone crystal structure distortion.

Shaking his head, Xu Chuan did the calculation again. After confirming that the result was correct, he calculated the interaction Hamiltonian and phonon spectrum of KL-66 material from scratch.

The calculation results of phonon spectrum found that both the undoped and copper-doped structures of KL-66 material have virtual phonon modes, indicating that the structure is unstable, which further confirms the results of formation energy calculation.

As for the interaction Hamiltonian, in the KL-66 material, Cu will form a high-density flat area at the Fermi level. Quantum geometry shows that this area is a strongly localized state, which is not conducive to the formation of superconductivity and is more likely to cause magnetism.

"Magnetism, a little interesting, is this thing a strong magnetic material?"

Staring at the calculated results, Xu Chuan thought for a while.

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 of formation energy, Hamiltonian, and phonon spectrum, it is very likely that it is a strong magnetic material.

And strong magnetic materials can also show the characteristics of semi-magnetic levitation in the paper and the video released by South Korea.

But it must be said that this matter has caused a lot of heated discussion on the Internet.

When Xu Chuan was teaching the next day, a student asked about this matter during the daily question-and-answer session after class.

"Professor, do you know about the KL-66 room-temperature superconducting material that has been very popular in South Korea recently? Is it true? What do you think?"

Xu Chuan smiled and teased: "Me? Of course I sat and watched."

Hearing this, the classroom burst into laughter.

Xu Chuan cleared his throat, coughed, and then said: "I do know about the KL-66 room-temperature superconducting material. But before the replica experiment comes out, I can't give a definite answer."

"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 studies and invents this material will undoubtedly win the Nobel Prize."

"And materials science will also usher in a great change. Its synthesis method will prompt us to focus on material synthesis in areas that have been neglected and abandoned before."

"It also means that in the previous material field, we have undoubtedly gone There are many detours. Perhaps some materials with extremely high performance can be synthesized in a simpler way. "

Hearing this, a student in the classroom immediately asked: "Then professor, do you think it is successful?"

Hearing this question, Xu Chuan thought about it and said: "If you 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 before it can be answered. "

"But today, I can talk to you. "

Hearing this answer, the classroom immediately pricked up a lot of ears, and even many students prepared their mobile phones and started recording videos.

Xu Chuan saw it, but didn't care too much. He continued, "After learning about the KL-66 material two days ago, the Chuanhai Materials Research Institute under my name has been conducting replication experiments."

"And out of interest, and because chemical material calculations are my area of ​​expertise, I did some calculations on some of the data provided in the paper on arxiv."

"Through three material calculations and simulations of the KL-66 material from the formation energy, Hamiltonian, and phonon spectrum. From the results, I am more inclined to believe that this material may be a strong magnetic material."

"First is the formation energy calculation. From the calculation results, it takes at least 10Mev of energy to replace the lead atoms in the KL-66 material with Cu atoms."

".So overall, I am more inclined to believe that it may be a strong magnetic material, rather than a room temperature superconducting material."

"Of course, this is not a definite answer, but based on the experiments I have done, Some speculations given by calculations. "

"At present, the Chuanhai Materials Research Institute under my name has been following up on the replication experiments in this regard. It is expected that the first to third batches of the replica KL-66 materials will be available the day after tomorrow. At that time, they will be tested to verify whether they have superconducting properties. "

"As for whether KL-66 is a room-temperature superconducting material or something else, everything needs subsequent replication experiments to truly answer. "

After a slight pause, he continued: "In addition, tomorrow I will sort out the calculation data I made, write it into a paper and send it to Arxiv. If there are interested students, you can go and have a look. "

"The above about some of my original material calculation mathematics is still very interesting. "

"I will also open a mathematics course for computational materials later, specifically teaching things in this area. Students who are interested can sign up later. "

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