It is still difficult to discover the properties of quantum systems made of many particles. The underlying mathematical equations are not easy to solve. A lot of new findings and applications in physics, chemistry and the material sciences are likely to be found if that barrier is broken.
The researchers at the Center for Advanced Systems Understanding have taken a major step forward by describing so-called warm dense hydrogen. Their work is in a journal.
For the first time, the scientists' approach can solve the fundamental quantum dynamics of the electrons involved when hydrogen atoms interact under certain conditions.
There is hydrogen in the universe. Our solar system's gas giant Jupiter is powered by the fuel that powers the stars. The most common form of hydrogen in the universe is not the odorless gas or the hydrogen-filled molecule that is found on Earth.
It is the warm dense hydrogen of stars and planets that causes electricity. Warm dense matter research focuses on matter under conditions such as very high temperatures or pressures found everywhere in the universe except for the surface of Earth.
The limits of simulation methods.
Scientists use simulations to try to understand the characteristics of hydrogen and other matter. Density functional theory is a popular theory. It has failed to describe warm dense hydrogen. Accurate simulations need to know the interaction of electrons in warm dense hydrogen.
Scientists have to rely on approximations of this interaction in order to get accurate simulation results. It's not possible to recreate the heat-up phase of ICF reactions accurately due to the knowledge gap. One of the major branches of fusion energy research could become a relevant zero- carbon power generation technology if this roadblock is removed.
The new publication shows for the first time the work done by the authors.
The path-integral Monte-Carlo method was extended to mimic the static electronic density response of warm dense hydrogen, according to Bhme. The method doesn't rely on previous approaches. The fundamental quantum dynamics are directly computed by it. Our approach to scale has its limits as it is very computation intensive. We can only handle particle numbers in the double-digit range because we rely on the largest supercomputers.
Still precise, higher scales.
The new method could result in benefits from the accuracy of the PIMC method as well as the speed and flexibility of the DFT method.
Scientists have been poking around in the fog to find reliable approximations for electron correlations. The results of the PIMC can be used to tune the settings of the DFT simulations. We should be able to give exact results in systems of hundreds to thousands of particles.
Enhancing DFT will result in better simulations of the behavior of any kind of material. The European X-Ray Free-Electron Laser Facility (European XFEL) and the Linac Coherent Light Source (LCLS) are examples of large-scale infrastructures.
The work of Bhme and his colleagues could possibly contribute to clarifying the details of how warm dense hydrogen becomes metallic hydrogen. It's possible to generate metallic hydrogen in the lab.
There is more information about the static electronic density response of warm dense hydrogen. There is a book titled "PhysRevLett.129.066."
Journal information: Physical Review Letters
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