In addition to news related to the manned space project, Wen Yuanhang also brought another news related to the establishment of the Large Strong Particle Collider project.
On the Thursday of the first week after New Year's Day in 2022, the Science Project Center is preparing to hold a discussion on building China's Large Strong Particle Collider.
This meeting was purely an internal meeting within the academic community, with only scholars from the high-energy physics and particle physics communities as well as relevant personnel in science and technology participating.
From site selection, to budget, to the implementation of technical details, all aspects need to be discussed and confirmed through meetings.
Xu Chuan definitely needs to participate in this meeting.
Apart from his demand for building a large strong particle collider, as a Nobel Prize winner in physics, his opinions are also crucial.
What's more, sterile neutrinos, dark matter, dark energy, and methods for mathematically calculating the energy orbits of physical particles are all related to him.
........
After Wen Yuanhang left, Xu Chuan turned his attention back to his work.
After handling some daily emails and related matters, he returned to NTU and took out the manuscript for calculating KL-66 materials from the drawer in his office.
Since we have to go to the capital for a meeting in another week, the matter of inviting Academician Sun Ze, the deputy chief designer of the lunar exploration project, will be handled together then.
As for the mechanism of KL-66 material, its importance has been elevated to a very high priority for subsequent research.
The most important thing is that there are not many people who can help him in this aspect, and it is difficult to find someone in China if he wants to cooperate with him in research.
The inversion asymmetric Cu atom spin-orbit coupling has a profound impact on the material band structure and electronic properties. The two branches of Fermi arc state electrons connecting the c-axis break the inversion symmetry theory.
Looking at the data and theories on the manuscript paper, Xu Chuan fell into deep thought.
The problem of strongly correlated electron systems is one of the core issues in condensed matter physics today.
But when it comes to this aspect, let alone China, there are not many breakthrough developments in the world.
More importantly, from the strong correlation phenomena discovered so far, the basic physical processes involved are often difficult to accurately describe in the existing physical framework, so this research is extremely difficult to handle through traditional experimental methods and theoretical methods.
Perhaps Mr. Yang Zhenhuan and Mr. Yang are a good candidate for communication. His research in condensed matter physics can be said to be the best in the world.
But now that he is ninety-nine years old, Xu Chuan really can't bear to disturb this old man's old age.
After thinking quietly for a while, Xu Chuan continued writing on the paper he wrote last time:
[Research on correlation effects and superconductivity in multi-orbital strongly correlated systems]
"S =(?kB/e)ln(ge/gh)......"
“Start with the tightly coupled interaction Hamiltonian: [H=i∑jTi,jai?i,σaj,σ i,i′∑j,j′Uii′a?iσa?i′σ′ajσ′aja]
"The second interaction term has a different contribution: [Uii′= Vi,i′→∑i,i′Vii′ inii′], that is, under density-density interaction..."
"From a physical point of view, this is because the two Vanier center wave functions must be antisymmetric, and the lowest energy state is the symmetric arrangement of the two spins (and the antisymmetric space wave function). When i→j is prohibited
Or when suppressed, that is, the overlap between adjacent orbits is very small, Uiii = U/2→ΣiVii′inii dominates, and the Hubbard model can be given."
"But how do you explain this theory mathematically?"
At his desk, Xu Chuan frowned as he stared at the theory he wrote on the manuscript paper.
The most troublesome point in the strongly correlated electron system is here.
“Is it OK to use a Hubbard model site?”
Thinking about it, he wrote a new line of formula: [H = Ht Hu =-t(a??↑a?↑ a??↓a?↓ h.c)]
This is the particle number conservation model. If half-filling (where strange physics occurs) is used, the Hilbert space consists of 6 states, including 2 fully polarized states |↑,↑> and |↓,↓> and
4 states with S?=0......
Theoretically, the first two states are self-contained states. And the Hamiltonian can be diagonalized in spaceSz = 0 of 4x 4.
On the manuscript paper, Xu Chuan was checking mathematical formulas and thoughts in his heart.
After a while, he stopped and finished counting.
The Hubbard model does work, but it cannot be used in a multi-site situation.
This is obviously not applicable to the mechanism in KL-66.
After the Cu atom replaced the lead site, it split into two Weyl nodes with opposite chirality through the Dirac cone, forming a multi-site effect. It is also the reason why the KL-66 material has strong diamagnetism and can even float in a strong magnetic field.
core mechanism.
"Perhaps, I should change the route and use Fermi fluid theory to calculate its electricity and magnetism."
Thinking about it, Xu Chuan changed his mind and started to set off.
It is extremely difficult to explain an unfamiliar mechanism, and he did not expect to find useful clues within a day or two.
I don’t know how much time passed before a voice came to me.
"Professor, you have your algebraic geometry class scheduled for this afternoon. Class starts in fifteen minutes."
In the office, the voice of his newly recruited student Rong Xinji rang out.
Hearing the sound, Xu Chuan came back to his senses, nodded and said, "Okay, I understand."
Out of curiosity, Rong Xinji glanced at the manuscript paper on Xu Chuan's desk.
His mentor has been sitting there frowning and studying something for most of the afternoon. He wanted to see what problems his idol was studying, and maybe he might have a chance to take advantage of it.
This chapter is not over yet, please click on the next page to continue reading! After all, I am also a graduate student and an IMO gold medalist, so I still have some strength!
How come he doesn’t even recognize mathematical symbols???
Before moving away from the manuscript paper with difficulty, he couldn't help swallowing and asked: "Professor, what are you studying?"
Xu Chuan glanced at him and asked with a smile: "Can you understand?"
Rong Xinji shook his head.
Can he say that he understands ghosts?
He is an IMO gold medalist and a graduate student in mathematics, but he doesn’t even know what the symbols in the formulas mean.
No one will believe you if you tell me this, okay?
It's so disappointing.
Hearing this, Xu Chuan smiled and said: "It's normal not to understand. This is not something in the field of pure mathematics."
After a slight pause, he then asked: "Do you know about the strongly correlated electron system in physics?"
In response to this question, Rong Xinji nodded. Although he was not a physics major, he still knew about such famous things as strong correlations.
Smiling, Xu Chuan continued: "These are the mathematical calculations of the relationship between correlation effects and superconductivity in multi-orbital strongly correlated systems."
Hearing this, Rong Xinji was instantly confused again.
Calculate what????
Looking at his student's confused look, Xu Chuan stood up with a smile and patted his shoulder, saying: "Study hard. If you are interested in mathematics and physics, you can read more physics books. In the future
You can also choose this as a PhD direction."
"As for now, it's not something you should be thinking about."