Chapter 456 When in Doubt, Use Quantum Chemistry!

After listening to the plan of the person in charge on the stage, Xu Chuan looked at Qin Anguo sitting next to him with a strange expression.

The mass catapult, the Nantianmen Project, and the space carrier were all things he had talked about with Wen Yuanhang a week ago.

Unexpectedly, I was immediately pulled up as a publicity today.

Noticing Xu Chuan's gaze, Qin Anguo turned around and smiled at him, saying, "I have to thank Academician Xu for your suggestion. Comrade Wen Yuanhang reported on these directions and developments after he came back."

"After discussion at the internal meeting of Xinmen, everyone felt that your suggestion was quite good, so they made a more detailed plan and used it in today's exchange meeting."

"After all, today's exchange meeting is open to the public, and with such a large-scale report, it must be able to attract some attention from the United States."

Xu Chuan touched his chin, thought for a moment and then said: "To be honest, I think the plan you came up with might actually be feasible. Things like mass catapults can indeed be done in theory. "

Hearing this, Qin Anguo asked curiously: "What do you say?"

Xu Chuan smiled and explained: "If it is just a simple manned spaceflight and lunar exploration project, there is really no need to build a large mass catapult."

"After all, the spacecraft required to carry out a manned spaceflight and lunar exploration project should theoretically not exceed one hundred tons."

"Even if we can't directly send a 100-ton spacecraft to the sky at once, we can still do it several times, and it won't cost too much money."

"But if you want to carry out large-scale lunar exploration, fire detection, or even establish a permanent scientific research and residential foundation on it, a simple and lower-cost transportation method is quite necessary."

"If you look at it from a long-term perspective, building a large-scale mass accelerator is still a good choice."

Qin Anguo thought for a while and asked: "If we build such a project, how much money and time will it take? Can it be done with current technology?"

Hearing this, Xu Chuan thought for a while and said: "Mass projectors are generally composed of giant electromagnetic guide rails, or they may be composed of coils, vacuum pipes and power supply systems."

"Any one of these three has huge engineering difficulties. The electromagnetic guide rail or coil is best composed of superconductors. Its huge superconductor requirements and corresponding low temperature requirements are almost unacceptable at present."

"However, as long as superconducting materials are further developed, this shortcoming can theoretically be solved."

"Secondly, the engineering difficulty of the vacuum super pipeline that is several kilometers vertical is also there. However, it can be built with the help of mountains such as Mount Everest. With the structural support of the mountain, this is not the most important."

"As for the energy supply problem, after controllable fusion technology is solved, electric energy is the easiest problem to solve."

"So in theory, it's possible."

"As for the funding, I did a simple calculation and found that this project is estimated to start at one trillion RMB."

"But the advantage is that after it is built, the price of each launch will be quite low. With this kind of thing, space activities can be carried out on a large scale in the future."

"If you are interested, I can ask someone to make a plan and budget for you after I go back."

Hearing the budget revealed by Xu Chuan, Qin Anguo smiled bitterly, shook his head and said: "Trillion, impossible, at least not now. It is impossible for the Development Committee to pass a project with this level of budget."

If it is controllable nuclear fusion, perhaps in the period when hope is seen, such as the demonstration reactor, this level of investment can still be passed. After all, China is extremely hungry for energy and spends 100,000 yuan on fossil fuel imports every year. The amount far exceeds this figure.

But aerospace engineering is almost impossible.

Even if the state could spare so much money, it would not be able to invest it in such a project. Isn’t it good to use it to mine resources on the earth? Do you have to go to space?

Why, the iron in space is better than the iron on earth?

Xu Chuan smiled and said, "In fact, compared to cultivating this on the earth, I am more optimistic about cultivating it on the moon."

"For mining helium-III deposits on the moon, due to the low gravity and airless environment, a large-scale mass projector is not needed to throw large-mass items to the earth."

Qin Anguo thought for a while and said with a smile: "This idea is quite special. I suggest you study it after I go back."

The two chatted, and the exchange meeting on the stage came to an end.

Apart from representatives from the Academy of Sciences and the Institute of Science and Technology, representatives from major aerospace fields and even some private enterprises that have nothing to do with aerospace, such as Goose Factory, Cat Factory and other enterprises, also came to the stage to give exchange reports. .

The former is mainly to share and exchange some technologies in the aerospace field, to promote business and visibility for their own companies, etc.

The latter said that he had ideas and budget to enter the aerospace field, or announced a satellite network plan or something.

Including Xu Chuan himself, at the request of Chairman Qin Anguo, he came to the stage to make a report on the development and direction of the aerospace field.

Of course, he did not speak much, mainly focusing on the field of electromagnetic propulsion.

After all, since the last time I talked with Academician Yang Hong, the aerospace electromagnetic propulsion system has been his preferred aerospace engine technology.

However, his fame is here, and the direction he talked about has been recorded by many people in academia, industry, and even the business community.

In short, the industry and business community can show themselves at the exchange meeting, meet partners, etc.

More importantly, investment in the aerospace field can be tax deducted at a ratio of one to two.

This is undoubtedly great news for those companies that pay large amounts of taxes.

Companies like Tencent have their own needs and reliance on satellites. This time, the state has subsidized the scientific research funds in the aerospace field in disguise, which will undoubtedly save them a lot of money.

And the country has also promoted the development of the domestic aerospace field through this exchange meeting.

Of course, more importantly, through this kind of exchange meeting, China's goals and plans in the aerospace field are made public, which is conducive to attracting the attention of Western countries led by the United States and dragging them into the track of the aerospace field.

And then delay the research progress of the other party in the field of controlled nuclear fusion, maintain its leading edge, expand China's influence in the international community, etc.

Today's meeting can be said to be a win-win for everyone present.

In addition to the daytime exchanges, this large-scale exchange meeting will also have an exchange party in the evening for the guests attending the meeting to get to know each other and make friends.

At the party, many people looked for the young figure in the venue with wide eyes, but to everyone's regret, that person did not come to the party.

At this moment, Xu Chuan has returned to Beihai Hotel.

For him, attending such a party does not make much sense, it is better to come back to study mathematics.

The research on correlation effect and superconductivity in multi-orbital strong correlation system has not been completed, and he has to hurry up to get this done.

After all, superconducting materials with high critical magnetic fields are the basis of miniaturized controllable nuclear fusion technology and aerospace electromagnetic propulsion systems.

In the hotel room, Xu Chuan, who once again eliminated a way, put down the pen in his hand, looked up and silently looked at the white ceiling.

In the past few days, he has eliminated many different routes through mathematics, and tried several different methods to calculate.

But in the end, he did not get any good results.

However, if the problem of studying correlation effects and superconductivity in multi-orbital strongly correlated systems is so easy to solve, it would not be a century-old problem in the physics world.

After a long sigh, Xu Chuan looked down at the manuscript on the table and rethought.

"The electron strongly correlated system is basically described from the perspective of condensed matter in most cases, but quantum chemistry can also explain this. Maybe we can try from quantum theory?"

Staring at the manuscript on the table, Xu Chuan fell into deep thought.

"Strictly speaking, the single electron (mean field) approximation does not mean that the interaction between electrons is ignored, but that the interaction between electrons is considered in the form of mean field, that is, the two-body operator is converted into a single-body operator through the trace with the single particle density matrix."

"But the mean field approximation does not mean that there is no correlation. Since the wave function of Hartree-Fock is antisymmetric (Slater determinant), there is actually a correlation between electrons with the same spin, which is called Fermi correlation."

"Therefore, the correlation effect that the mean field approximation really lacks is the so-called Coulomb correlation."

"If we want to calculate this kind of general correlation, we have to start with the specific form of the wave function. The approximate wave function used by the mean field approximation Hartree-Fock is called the Slater determinant, which is the product of the single electron wave function and then antisymmetric and satisfies the Pauli incompatibility."

Thinking, Xu Chuan involuntarily picked up the pen on the table again and wrote on the manuscript paper:

[|Ψ>=c0|Φ>+∑i, aCai>+∑ij, abCab/ij>+···（eqn 1)】

From the ground state configuration, the single electron wave function |Φ|\Phi\rangle|\Phi\rangle is a good approximation of the multi-body wave function |Ψ|\Psi\rangle|\Psi\rangle, indicating that the Coulomb correlation is very small.

In the weakly correlated system, the mean field approximation can qualitatively describe many properties of the system, but there are some quantitative deficiencies, which come from the contribution of those excited configurations that account for a small proportion.

In other words, it can be generalized!

Perhaps, starting from the field of quantum chemistry, it is really possible to find a mathematical path to the correlation effect in multi-orbital strongly correlated systems.

Staring at the data on the manuscript, Xu Chuan's eyes flashed with excitement.

He may have found a breakthrough.

But how far this mouth can take him is not yet known.

PS: There is another one in the evening, please vote for the monthly ticket!