Princeton's mathematics department is ranked No. 1 in the world, and other universities should have little opinion.

Princeton's physics department is very strong, ranked in the top seven in the world.

Harvard, Stanford, Princeton, MIT, Cambridge, Oxford, Caltech, these universities have their own characteristics and fist projects, their points on the physics ranking list are relatively close, who wants to be the boss of the physics community, the remaining six always have people who are not convinced.

The Department of Physics at Princeton focuses on condensed matter physics, cosmology, and high-energy physics, and Hackman is a professor in the field of condensed matter physics in the Department of Physics at Princeton.

Hackman wouldn't be here to smash the field, would he...... Shen Qi is silent, and responds to all changes with no change.

Unexpectedly, Hackman opened his mouth and said, "Shen, our physics department needs you." ”

"Huh?" Shen Qi smiled faintly, allies?

Hackman: "Your paper published in PRL, based on the topological processing of homotopy groups, redefines defects in continuum and crystals, which is of great reference value to us. ”

"Uh-huh. Shen Qi suddenly brightened, and it was indeed a friendly army.

"I don't care about purely mathematical problems, but Shen, you also have a deep study in physics, and your presence is very precious to us. Hackman said.

What Hackman said made Shen Qi sound quite comfortable, and he showed a friendly attitude: "Say, Professor Hackman, what do you need me to do?"

Hackman saw that Shen Qi had a copy of the latest PRL on his desktop, and he flipped the PRL to the section "Defect Topology Based on Spherical Stable Homotopy Groups" and asked, "How is this cohomology group on the Adams spectrum calculated?"

"Didn't I write it in my paper?" Shen Qi asked rhetorically.

"The calculations are beautiful, but your calculations are ...... How to put it, it's more complicated. That's right, I happen to have a project at hand, and I need to cite the theoretical basis in your paper, mainly in terms of mathematical processing, so it's better to ask clearly. Hackman said.

Shen Qi finally understood Hackman's intention, this old brother didn't understand it, so he came to ask for advice, this kind of truth-seeking and pragmatic academic attitude is worthy of recognition. It is important to know that not every physicist with many honors and titles is as proficient in mathematics as Edward Witten.

"Professor Hackman, that's right, let me explain that in the study of the structure of matter in condensed matter physics, I use this mathematical processing method to derive the short orthozygotic ......sequence of cohomology groups on short Zp," Shen Qi patiently explained his calculation method.

"OK, excellent. Hackman understood, and he shook hands with Shen Qi: "Thank you, you have time to come to my office in the Department of Physics for coffee." In addition, I would like to make a suggestion, in the future, when you write physics papers, can you appropriately attach some experimental data or computer simulation data, so that more physicists can understand your theory? If everybody came to your office to inquire like I did, and you were so enthusiastic, you would be as busy as our president. ”

Shen Qi nodded: "I accept your suggestion, Professor Hackman, by the way, you said that you would cite my paper in your research project, so it is convenient to reveal what your project is mainly researching?"

"Of course, you have the right to know that inspired by graphene, my project is mainly to study the electronic structure and optical properties of graphitic nitrogen carbide quantum dots, and it has been difficult to analyze various microstructures in materials using traditional condensed matter physics methods. And your defect topology method based on spherical stable homotopy groups is so helpful to me, thank you again, Professor Shen. Hackman thanked Shen Qi and left with a fruitful harvest.

There is some truth in Professor Hackman's suggestion, my paper is so mathematically strong that in most people's minds, I am still a mathematician...... Shen Qi opened the ADF software on the computer and strengthened his physical and chemical properties.

ADF is a computer simulation analysis software, Shen Qi has been installing it for several months, occasionally playing with it, and most of his work relies on brain supplements.

The research results of pure brain supplementation, Professor Hackman came to complain, but he couldn't understand it.

So Shen Qi operated ADF, and he needed to change some ways of working, at least in the current stage of physics research.

ADF is widely used in materials chemistry, solid state physics, catalysis, batteries, spectroscopy and other fields, it can simulate chemical reactions, construct microstructures, calculate various data, and has complete functions.

Most of the real-world operations performed in the laboratory can be simulated by ADF, which can save a lot of experimental costs.

"Graphitic nitrogen carbide, g-C3N4, this is a new synthetic material, powdery at room temperature and pressure, non-toxic. ”

Shen Qi checked the information and had a general understanding of graphitic nitrogen carbide, he had never seen the real thing, but he was already making changes, at least he tried to understand the real thing.

In today's increasingly serious pollution, energy and environment are the two major problems faced by all countries, and solar energy, a clean energy source, has received extensive attention from all countries.

Photocatalysis is considered to be a promising technology for converting low-density solar energy into high-density chemical energy, but traditional semiconductor photocatalysts such as TiO2 have low light absorption efficiency due to their large internal structural defects.

Therefore, it is imperative to find a new type of photocatalyst that can have strong activity under visible light, so graphitic nitrogen carbide g-C3N4 was synthesized by scientists.

g-C3N4 is of higher quality than TiO2, but the new synthetic material itself is flawed and still does not meet the ambitions of scientists.

By doping metal or non-metal atoms with G-C3N4 to forcibly change the microstructure, optical, electrical and other physical properties of G-C3N4, scientists will achieve the goal of efficient conversion of solar energy, and finally solve the problem of pollution and benefit mankind.

Professor Hackman's team in the Department of Physics next door is engaged in this great cause of benefiting mankind and saving Mother Earth.

Professor Hackman wondered which element was incorporated into which part of g-C3N4 in what way to achieve the best results.

This goes back to the basic theoretical research of condensed matter physics, can the microstructure analysis and defect definition of condensed matter be optimized?

In the article "Research on Defect Topology Based on Spherical Stable Homotopy Group", Shen Qi proposed a theoretically feasible optimization scheme, which gave Professor Hackman hope.

When Shen Qi drafted this paper, he did not pay attention to new materials such as graphitic nitrogen carbide, he did macroscopic theoretical research, and did not care too much about specific material applications.

Now Shen Qi has become curious about specific substances, and mathematics, physics, and chemistry are deeply integrated and crisscrossed in his heart at this moment.