Chapter 445: Working Hard Is a Necessary Skill!

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

However, this is almost the last flash of light.

After all, the magnetic levitation mechanism of KL-66 has been explained accordingly. Unless a subsequent research team can observe the Meissner effect on the reproduced KL-66 material, it is basically impossible to have a turning point.

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

Even South Korea’s own research institutions, the South Korean Superconducting and Low Temperature Society, have publicly announced that "no results have yet confirmed that KL-66 materials have superconductivity."

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

Xu Chuan did not care about the turning point of the news in the outside world. He has returned to Nanjing University and is doing derivation and research in his office.

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

On the contrary, he discovered a novel atomic doping structure on this antimagnetic material.

The inversion asymmetric spin-orbit coupling of Cu atoms has a significant impact on the material's band structure and electronic properties. The core is that the two branches of the Fermi arc state electrons connect the c-axis, breaking the inversion symmetry.

This leads to the splitting of the Dirac cone into two Weyl nodes with opposite chirality, resulting in non-trivial quantum phenomena.

This is the core mechanism for the strong antimagnetism of KL-66 materials and even their ability to float in strong magnetic fields.

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

He is exploring the secrets behind this phenomenon.

"Professor, you're back."

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

If you ask a question on βhu: "What is it like to have a top-notch mentor who is a Nobel Prize winner?"

He Cai Peng is absolutely qualified to answer!

First of all, it is certain that it is good to study with such a top-notch person.

However, what makes people despair is that most of the time, a tutor of this level is not in the office, either participating in national projects or busy with their own things.

Like him, he has been with his tutor for more than two years, and he has met his tutor only a few times.

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

If the tutor you meet has high requirements for graduation, it will be even worse.

Fortunately, he still has a senior brother. Although Gu Bing has graduated and left, he is still a mathematics professor at Nanjing University.

When he encounters some problems, he can still ask this senior brother for help.

But relatively speaking, he studies differential equations, while Gu Bing studies algebraic topology and analytic geometry. Many times he can't guide him.

In this case, all he can do is send the questions to Xu Chuan through WeChat or email.

Although he can basically receive answers, asking questions through these methods is definitely less efficient than asking questions face to face.

Of course, he could understand this situation, after all, his mentor was really too awesome.

But he understood, but he felt miserable not being able to see anyone for years, like a left-behind child.

Hearing the voice, Xu Chuan looked up, nodded with a smile, and asked, "How is the problem I gave 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 for him later.

However, because of the KL-66 material issue in South Korea, he was delayed for a while, and the three days he said at the beginning must have passed.

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

In fact, it has been more than ten days since I got this problem.

He also studied the problem on the manuscript paper for more than ten days, but he didn't solve it, but he must have some ideas and thoughts.

Xu Chuan nodded, took the manuscript, and read it carefully.

"Your foundation is okay. You have made progress in the past two years." After reading the answer sheet, Xu Chuan smiled and said, "But you have taken a lot of detours in some aspects."

As he said, he stood up and dragged a blackboard from the corner of the office. He wrote and pointed out: "For example, when solving this module, you used Gaussian elimination to perform elementary row transformations on the augmented matrix (A|b) and converted it into a ladder matrix for processing."

"This method is correct, but don't you think it's a bit too complicated?"

Looking at the formula on the blackboard, Cai Peng scratched his head and said, "It's okay? I think Gaussian elimination should be very suitable for use here."

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

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

Xu Chuan smiled and nodded, saying: "That's right, when the coefficient matrix A is strictly diagonally dominant or symmetric positive definite, the Gauss-Seidel iteration must converge. Starting from this aspect, it will be easier than the Gaussian elimination method you used."

After a slight pause, he continued: "Solving a system of linear algebraic equations is one of the most basic problems in scientific and engineering calculations. Most of the computational problems ultimately come down to solving a system of linear algebraic equations."

"The main difficulty in solving large-scale linear equations lies in its workload. How to reduce its workload is the key you should think about."

"Of course, I am also negligent here. I really didn't teach you anything in the past two years. But I should be in the office for the next few months, so I can teach you well."

In the office, Xu Chuan picked out some questions for Cai Peng's answer sheet and gave instructions.

Maybe because of his own experience, whether in his previous life or this life, he taught himself more. Therefore, for the students he led, he also tended to let them go.

However, this method is not suitable for everyone. And even if you let them go free, you still need to teach them some core theories and thinking methods, otherwise they will go astray or fail to understand the core sooner or later.

After half an hour, Xu Chuan stopped and said, "Let's stop here today. You should absorb and digest what I said in the next two days."

"In addition, I will list a few books. You should read them carefully in the next two months. You still lack a lot of knowledge points and need to learn."

As he said, he wiped the formulas on the blackboard, thought for a while and wrote: "Elementary Differential Equations and Boundary Value Problems", "Special Function Theory", "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 now. I'll give you three months to study. If you have any questions in the middle, you can always come to me. I will come to test your learning results after three months."

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

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

Big brother! This is not an online novel, it's a math textbook!

Suddenly, he remembered what Senior Brother Gu Bing had said to him before: "To study with a mentor, working hard is a necessary skill!"

On the first day when the mentor came back to teach him, he realized what it meant to work hard as a necessary skill.

After letting Cai Peng learn by himself, Xu Chuan sat back at his desk.

He began to think again about the possibility of making a complete connection between strong antimagnetic materials and band topology.

The problem of strongly correlated electronic systems is one of the core issues in today's condensed matter physics.

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

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

Then it shows macroscopic quantum phenomena such as high-temperature superconductivity and giant magnetoresistance, giving the material new properties with great application value.

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

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

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

[Research on correlation effect and superconductivity in multi-orbital strong correlation system]

"S = (kB/e)ln(ge/gh)"

Just after writing a title, before he could go into it, the door of the office was knocked.

"Come in." Xu Chuan responded. The person who came to him was Tan Shaoyuan, the new president of Nanjing University.

"Academician Xu, regarding the matter of recruiting students you mentioned last time, I have asked someone to do a preliminary screening here. Here is the list, please take a look."

Tan Shaoyuan greeted with a smile and handed over the list 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 run a trip. Please send it here in person, President Tan."

Tan Shaoyuan smiled and said: "It's no trouble to run a trip on the way."

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

"Well, please go ahead."

Tan Shaoyuan coughed lightly and said: "Last time when you were teaching, Academician Xu, you said that you were going to open a course on computational materials science at Nanjing University. I want to ask about this."

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

Apart from these, for schools with this course, it is definitely a matter of expanding the school's academic atmosphere and international reputation.

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

However, Xu Chuan had already left Nanda at that time and went to the Sichuan-Hai Institute of Materials to do experiments. He did not come back until today. But this time, he couldn't wait to come to the door and wanted to ask about the situation.

The leadership position of Nanjing University is a very rare one in today's academic world.

After all, here is the number one academic person in China and even the world. As long as he is still at Nanjing University, he can achieve various results in 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, I have some understanding in the field of computational materials science, and I wanted to see if I can spread it."

Hearing this, Tan Shaoyuan quickly said: "Then I will make arrangements here and get the relevant work done as soon as possible."

Xu Chuan said with a smile: "There is no need to rush this. Although I have ideas in this regard, my time here is not stable. If I open a subject specifically, I am worried that I will miss the students who apply for this subject."

After thinking for a while, he spoke again: "Well, let's not treat the computational materials mathematics course I teach as a major or minor. Let's open a special course on technological innovation here at Nanjing University."

"I hold classes here from time to time and give advance notice, and then interested students can come and listen. When the situation here becomes more stable, I will offer special courses."

He did originally offer a course on computational materials science, but when he was studying KL-66 materials, he accidentally discovered something in a strongly correlated system.

Later, during the research process, it was discovered that it seemed to promote the miniaturization of controllable nuclear fusion devices, so the idea of ​​starting a class was cancelled.

After all, compared with the importance of miniaturized and controllable nuclear fusion reactors, setting up computational materials courses is dispensable.

Hearing this, Tan Shaoyuan nodded with a smile and said, "Yes, Academician Xu, you can arrange it. If you need to start classes, you can tell me at any time and I will help arrange it."

Xu Chuan smiled and said, "No problem."

"Then I won't disturb Academician Xu's work."

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

"Professor, do you want to recruit new students?"

In the office, Cai Peng, who had been silent for the whole time, looked over curiously after Principal Tan left.

Xu Chuan nodded and said, "Well, I will take advantage of the relatively leisure time in the past few months to take some students with me."

Cai Peng asked excitedly: "Then I will be the senior brother from now on?"

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

Cai Peng: "\φ(゜▽゜*)\"