Chapter 1340: Implicit density functional method

Young's modulus ≥21tpa, failure strength ≥80n / ……
Judging from the series of parameters given here, Lu Zhou first thought of a cable with a very high tensile strength, and then thought of an impact-resistant coating for automotive or aerospace equipment. .
As for where this stuff can be used ...
That would be more useful.
Simply speaking, it can be used as a cable. From the sky, it can be used on the space station. It can be used as a traction rope to fix the heat sink and solar panel. It can be used as a suspension material for engineering equipment when it is placed on the ground. As a blocking cable on the carrier deck.
Especially the latter, this stuff is not generally expensive.
And these are just one of the uses for this material.
Lu Zhou believes that after this kind of material with high Young's modulus and high breaking strength comes out, there must be countless people who can come up with them for uses that he did not even think of.
Back to the study itself.
For the technical standard given by the system, the best option that Lu Zhou can think of is to have a carbon-based material with high tensile strength, light weight and strong plasticity.
In particular, a series of graphite-derived reinforced composites such as carbon fiber.
This kind of material not only has a broad imagination space in theory, but also the research of computational materials science, it is his old profession. When he first did computational materials research, he started with carbon materials.
Therefore, it can be said that this task is not difficult for him at all.
It's almost like giving it away!
After leaving Professor Wang Qingping's laboratory, Lu Zhou did not stop at the Jinling Institute of Advanced Research, but went straight home.
When he modified that mathematical model against the experimental results, he suddenly had some ideas about theoretical research on computational materials science.
Perhaps because of both mathematics and physics rising to lv10, Lu Zhou found that he was sensitive to numbers and physical phenomena and had reached a state of myth.
Even if it was just a clue that was so small that it was almost negligible, it could be magnified infinitely in his eyes and turned into a key that could be touched with both hands.
No matter where this inspiration came from, he had only one idea at the moment.
That is, while the inspiration has not yet dissipated, record it.
After going upstairs to the study, and ordering Xiao Ai to help him make a cup of coffee, Lu Zhou sat at the desk, and the draft paper brought back from the laboratory was laid on the table.
"The material a synthesized according to the experimental process designed by the original model has a low density, and after the deposition, a fluffy mass is formed, and the diameter of the carbon nanotubes is extremely uneven ..."
"The reason for this result should be the insufficient polymerization of the monomer acrylonitrile through radical polymerization, which formed a large number of intermediate products, which led to the inadequate third-stage reaction ... and finally formed that foamy mixture.
"Well, interesting."
What attracted Lu Zhou's interest was not the foamy mixture, but some very interesting phenomena he discovered when he revised the calculation model.
After thinking about it for a while, he picked up his pen and wrote a line neatly on a blank piece of draft paper.
[Implicit density functional method]
Looking at the inspiration that this line was refined into words, the corner of Lu Zhou's mouth could not help pulling a hint of smile.
Generally speaking, when a problem is clearly written, it is half solved.
At least for him!
The so-called implicit functional density is a method of computational materials science relative to explicit functional density. It is a relatively popular research direction in the theoretical research field of computational materials science.
As we all know, the traditional exchange-related energy functional is an explicit functional that is directly expressed by the electron density function, and the representation method that uses the khn-han orbital wave function as a direct variable is an implicit functional.
The simplest implicit functional is fk exchange energy, which is often called exact correlation in the context of density functional theory.
For molecular systems, the use of implicit functional can achieve the accuracy equivalent to the second-order multibody perturbation theory with a relatively small amount of calculation. Therefore, the implicit density functional method is widely regarded as a kind of Prospective Computational Materials Science Research Methods.
However, despite the similarities, the disadvantages are obvious. Such as limited accuracy, including the inability to accurately describe Van der Waals interactions, etc., which is almost fatal for the study of solid materials.
Therefore, the implicit density functional method has been applied relatively little in the study of solid materials, and has only made some progress in some fields ... And this is still under the situation that the computing power has been greatly developed.
At present, the widespread concern in the academic community is the implicit correlation functional based on the adiabatic correlation fluctuation dissipation theorem, which is widely regarded as a breakthrough to overcome the deficiency of implicit functional density.
However, the problems of such functionals are not small, especially the huge amount of calculations can be tricky even for the most powerful traditional computers. Therefore, the current research direction is still on the exploratory research of simple systems.
What Lu Zhou needs to do at this moment is to extend this method from a simple system to the research of relatively complicated carbon materials!
Once this research is successful, it will be of great help to the entire research field of carbon composite materials, and its significance will even surpass the material he studied "Young's modulus ≥ 21tpa, breaking strength ≥ 80n / ......" !!
The stroke of the pen in his hand didn't pause at all, and after finishing the title, Lu Zhou quickly dived into the exploration of the proposition itself.
[According to the h-k theorem, the ground state energy functional can be expressed as: eg {p (r)} = e {p (r)} ∫v (r) p (r) dr ……】
[The functional e {p (r)} can be expressed as: e {p (r)} = t {p (r)} 1/2 ∫ ∫ {p (r) {p (r) drdre {p (r )} ...]
[……]
Lines of formulas flowed from under the nib, just like a trickling stream, together with the inspiration that erupted into a river, rushing into the sea!
All the inspirations about matter, at this moment are visible figures, weaved into a language that can be recited.
Under the shroud of this huge net, all forces and physical characteristics are included, all abstracted into the language of mathematics by the rigorous and trembling logic ~ EbookFREE.me ~ and mathematical methods Answered!
"Then, the hrdger equation is introduced."
With a quiet meditation in his mouth, the pen edge pinched by Lu Zhou at his fingertips was like a sharp dagger, drawing a powerful trajectory on the paper, and also piercing the thick covering the end of the maze. fog.
Looking at the result almost on the paper, Lu Zhou's pupils became brighter, and his slightly frowned brows finally relaxed a radian of smile.
Although there is still no way to go from the end.
But his intuition about science had told him that he was very close to the end!
Time passes by every minute.
The sun gradually moved from the upper air to the corner of the sky.
With the sky finally darkening, the street lights on both sides of the tree-lined path began to light up. At this moment, Lu Zhou finally raised his head and took a breath, stopped the pen that was almost pinched in his hands.
"... The implicit density functional method also has broad prospects for the study of carbon composites, at least now it has been extended to this field."
"At the same time, this can be regarded as a breakthrough to extend the method from a simple system to a complex system."
"Although there is still room for further excavation."
"But that's it for now."
After all, Lu Zhou smiled with satisfaction, and put the pen in his hand aside.
And almost at the same time he had just dropped the pen, a line of pale blue text unexpectedly appeared to his eyes.
At first he thought he was wrong, and Lu Zhou blinked subconsciously.
However, the line of pale blue text was not half dimmed by his blink, it was still so clear and cannot be ignored ...
[Congratulations to the host, complete the mission! 】