With the two papers that Xu Chuan threw on arxiv, the discussion about the KL-66 material once again set off a wave on the Internet.

But this is almost the last time to shine back.

After all, the magnetic levitation mechanism of KL-66 has been explained, and unless a subsequent research team can observe the Meissner effect on the reproduced KL-66 material, it is basically impossible to make a transition.

In the next few days, the replication results released by scientific research teams in various countries can be regarded as a comprehensive confirmation that LK-66 is not a superconductor.

Even South Korea's own scientific research institute, the South Korean Society for Superconductivity and Cryogenics, has publicly announced that "no results have yet confirmed the superconductivity of KL-66 materials."

Although it is unfortunate that a new path has not been found in the field of materials, this is not the first time that such news has appeared in the field of room-temperature superconductivity.

Xu Chuan did not change the news in the unexpected world, this will be that he has returned to NTU, and is doing derivation and research in his office.

Although it has been confirmed that KL-66 is not a room-temperature superconductor after calculations and replication experiments, his research on it is not a waste of time.

On the contrary, on this diamagnetic material, he discovered a novel atom-doped structure.

The spin-orbit coupling of the inverted asymmetry of Cu atoms has a significant impact on the band structure and electronic properties of the material, and the core of the coupling is that the c-axis of the two branches of the electrons in the Fermi arc state breaks the inverse symmetry.

This in turn causes the Dirac cone to split into two Weyl nodes with opposite chiralities, resulting in non-trivial quantum phenomena.

This is the core mechanism of KL-66 material showing strong diamagnetism and even floating in strong magnetic fields.

It is also a phenomenon that has never been discovered in the field of physics and materials science.

It is the secret behind this phenomenon that he explores.

"Professor, you're back."

In the office, Cai Peng walked in, saw Xu Chuan sitting behind the desk at a glance, and shouted in surprise.

If you ask a question on β: "What is it like to have a mentor who is a Nobel Prize winner?" ”

He, Cai Peng, is definitely qualified to answer!

First of all, it is certain that it is good to learn from such a top expert.

However, what is often desperate is that most of the time of the tutor at this level is not in the office, either working on national projects or busy with their own things.

Just like him, he has followed his mentor for more than two years, and he has met his mentor in person, which can be said to be one of the few.

For students, most of the time they are like left-behind children, learning everything depends on self-consciousness or looking for brothers and sisters.

If you meet a mentor who has high requirements for graduation, it will be even worse.

Fortunately, he also has a senior brother, although Gu Bing has graduated and left, he is still a professor of mathematics at NTU.

When he encountered some problems, he could still find this senior brother for help.

It's just that relatively speaking, he studied differential equations, while Gu Bing learned algebraic topology and analytic geometry. A lot of times I can't guide him.

In this case, all he can do is to send the question to Xu Chuan through his prestige or email.

Although you can basically receive answers, asking questions in these ways is definitely much less efficient than asking face-to-face questions.

Of course, he can also understand this situation, after all, his mentor is a bit too 'bull β'.

But understanding is understanding, but he can't see anyone all year round, and he is always like a left-behind child, and he is also bitter in his heart.

Hearing the voice, Xu Chuan glanced up, nodded with a smile, and asked, "How did you do with the question that was given to you before?" ”

When he came back last time, he wrote a question to this student to check his skills in the past two years, so that he could make a targeted course arrangement in the future.

However, due to the KL-66 material on the South Korean side, it was delayed for a while, and the time must have passed for three days.

Cai Peng nodded, walked quickly to his position, found the manuscript paper from the drawer, respectfully handed it to Xu Chuan, and said, "The top stack is my thoughts in the first three days, and the lower part is some of my thoughts these days." ”

In fact, more than ten days have passed since I got this question.

He also studied the problems on the manuscript paper for more than ten days, but he couldn't solve them, but there must still be some ideas and reflections.

Xu Chuan nodded, reached out to take the manuscript paper, and read it carefully.

"The foundation is okay, and there has been progress in the past two years." After reading the answer sheet, Xu Chuan said with a smile: "But you have taken a lot of detours in some aspects. ”

As he spoke, he got up and dragged out a blackboard from the corner of the office, and pointed while writing: "For example, when solving in this module, you used the Gaussian elimination method to transform the augmented matrix (A|b) into a stepped matrix and then process it. ”

"That's true, but don't you think it's a little too complicated?"

Looking at the equation on the blackboard, Cai Peng scratched his head and said, "Okay?" I think it would be appropriate for Gaussian to be applied here. ”

Xu Chuan smiled and said, "Then do you remember the iteration?" ”

Cai Peng thought for a moment, his eyes suddenly brightened, and blurted out: "Gauss-Seidel iteration!" ”

Xu Chuan nodded with a smile and said, "That's right, when the coefficient matrix A is strictly diagonally dominant or symmetrically positive, the Gauss-Seidel iteration must converge, and starting from this aspect will be more convenient than the Gaussian elimination method you use." ”

After a slight pause, he continued: "Solving systems of linear algebraic equations is one of the most fundamental problems of scientific and engineering computing, and the vast majority of computational problems ultimately boil down to solving systems of linear algebraic equations. ”

"The main difficulty in solving large-scale linear equations lies in the amount of work, and how to reduce it is the key you should think about."

"Of course, there is also my dereliction of duty here, and I really haven't taught you anything in the past two years. But I'll be in the office for the next few months, so I can teach you a little bit. ”

In the office, in response to Cai Peng's answer sheet, Xu Chuan picked out some questions and taught.

may be due to his own experience, whether it is in his previous life or in this life, he is more self-taught. Therefore, for the students he brings, he is also free-range.

But it's not for everyone. And even if it is free-range, it is still necessary to teach some core theories and ideological methods, otherwise sooner or later it will deviate or fail to understand the core.

After half an hour, Xu Chuan stopped and said, "Let's get here first today, you can absorb and digest the things I talked about in the past two days." ”

"In addition, I will list a few books, you can take a good look at them in the past two months, and you still lack a lot of knowledge points and need to learn."

As he spoke, he erased the equations on the blackboard, thought about it and wrote: "Elementary Differential Equations and Boundary Value Problems", "Theory of Special Functions", "Numerical Solutions of Differential Equations", "Mathematical Methods in Physics and Engineering", ". 》

After listing six or seven books, he threw the chalk in his hand into the chalk box, clapped his hands, and said, "That's it for the time being, I'll give you three months to study, and if you have any problems in the middle, you can always come to me, and I'll test your learning results after three months."

Looking at the six neatly listed books on the blackboard, Cai Peng couldn't help but swallow dryly.

Six books, three months, an average of two books a month!

Big guy! This is not the Internet, it is a math textbook!

Suddenly, he remembered what Senior Brother Gu Bing had said to him before: "Learn from the tutor, bursting the liver is a necessary skill!" ”

On the first day when the instructor came back to teach him, he realized what it means to burst the liver is a necessary skill.

After letting Cai Peng go to school by himself, Xu Chuan sat back at his desk.

We are starting to think about the possibility of a complete correlation between strong diamagnetic materials and band topology.

The problem of strongly correlated electronic systems is one of the core problems of condensed matter physics today.

In materials such as complex transition metal oxides (TMOs), the collective behavior of the system electrons determines its macroscopic properties due to the strong electron-phonon or electron-electron coupling, and the simple superposition of individual electron kinetic energy no longer plays a dominant role.

With the change of external conditions such as temperature and magnetic field, the lattice structure, electronic structure, spin arrangement and other order parameters of the material are entangled with each other, resulting in an extremely rich phase diagram structure.

Furthermore, macroscopic quantum phenomena such as high-temperature superconductivity and pangreoresistive are demonstrated, which give the materials new properties with great application value.

There is no doubt that this new phenomenon found on the KL-66 material belongs to the strong electronic correlation system.

But if the system is integrated into the mathematical language and explained, it is quite troublesome.

After thinking for a while, Xu Chuan took out a stack of manuscript paper from the drawer.

【Study on Correlation Effect and Superconductivity in Multiorbital Strong Correlation System】

“S =(kB/e)ln(ge/gh)”

As soon as he wrote a headline, before he could expand further, there was a knock on the office door.

"Please come in." Xu Chuan answered, and it was Tan Shaoyuan, the new president of NTU, who came to him.

"Academician Xu, regarding the matter of recruiting students you said last time, I have already asked people to do a preliminary screening, the list is here, you can take a look."

After Tan Shaoyuan said hello with a smile, he handed over the list materials in his hand.

Xu Chuan took the list and said with a smile: "Thank you, but for this kind of thing, just arrange an assistant or secretary to go on a trip, and please talk about the principal, you can send it over in person." ”

Tan Shaoyuan said with a smile: "Take a trip along the way, what's the trouble." ”

After a slight pause, he continued: "This time, in addition to the list, there is one more thing I want to ask. ”

"Well, please."

Tan Shaoyuan coughed lightly and said, "Last time Academician Xu, you said when you were teaching, that you are going to open the course of computational materials science here at NTU, and I want to ask about this matter." ”

A Nobel laureate, and a scholar who is known as the father of controlled nuclear fusion, this kind of top-notch course will be greatly welcomed and attract countless talents no matter which country or university it is placed in.

Putting these aside, for schools with this course, it is definitely a proper thing to expand the school's academic atmosphere and international reputation.

Therefore, more than ten days ago, after Xu Chuan finished that class, he came to the door with concern.

However, at that time, Xu Chuan had already left Nanda and went to the Chuanhai Materials Research Institute to do experiments, and he didn't come back until today, and this time he came back, he couldn't wait to come to the door and wanted to ask about the situation.

The position of the leader of Nanda University, in today's academic circles, is a proper fragrant bun.

After all, there is the first person in the academic community in China and even the world, as long as he is still at NTU, he can make various achievements for a few years.

Hearing this question, Xu Chuan suddenly remembered what he had said in class before.

Smiling, he said: "I had this idea before, after all, in the field of computational materials science, I still have some understanding, and I want to see if I can spread it." ”

Hearing this, Tan Shaoyuan quickly said: "Then I'll arrange it here and do the relevant work as soon as possible." ”

Xu Chuan said with a smile: "There is no need to rush this, although I have this idea, but my time is not stable, if I open a subject, I am worried that I will miss these students who apply for this subject." ”

After thinking about it, he re-spoke: "In this way, the computational materials mathematics course I teach should not be a major or minor, let's open a special course of technological innovation here at NTU." ”

"I hold classes from time to time, with advance notice, and then interested students can come and listen. When the situation on my side is a little more stable, let's start a special course. ”

Originally, he did take a course in computational materials, but while studying KL-66 materials, he accidentally discovered something in the strongly correlated system.

Later, in the course of research, it was found that it seemed to promote the miniaturization of controlled nuclear fusion devices, so the idea of starting the course was cancelled.

After all, compared to the importance of miniaturized controllable nuclear fusion reactors, a course on computational materials is a dispensable.

Hearing this, Tan Shaoyuan nodded with a smile and said, "Yes, you can arrange this kind of Academician Xu." If you need to start a class, you can always tell me and I'll help arrange it. ”

Xu Chuan smiled: "No problem. ”

"Then don't disturb Academician Xu's work."

Tan Shaoyuan left the office with a smile, and Xu Chuan picked up the list materials in his hand and looked at them.

"Professor, are you looking for new students?"

In the office, Cai Peng, who had not spoken, looked curiously after the principal left.

Xu Chuan nodded and said, "Well, taking advantage of the fact that there should be some relatively leisure time in the past few months, I am going to take a few students." ”

Cai Peng asked excitedly: "Then I will be a senior brother in the future?" ”

Xu Chuan glanced at him and said, "You better think about how to graduate." ”

Cai Peng:"\φ( ゚▽ ゚*)\"