New discovery allows physicists to predict properties of any atom
International collaboration of physicists have led to a new methodology that enables precise calculation and prediction of the properties of any atomic nuclei.
The international research team on "Nuclear Lattice Effective Field Theory”, including researchers from Institute for Rare Isotope Studies (IRIS) and Center for Exotic Nuclear Studies within the Institute for Basic Science (IBS), developed a "Wave Function Matching” methodology that can precisely calculate properties such as binding energy, mass, and charge radius of various atomic nuclei. This finding is expected to be of significant importance in future research on rare isotopes utilizing heavy ion accelerators.
Although nuclear physicists have conducted extensive research on nuclear forces between atomic nuclei and their constituents (nucleons), it has been challenging to explain the properties of atomic nuclei, such as binding energy, mass, and charge radius, solely based on nuclear forces between nucleons. Researchers have traditionally resorted to case-by-case approach, choosing suitable model depending on the intended calculations and targets. In the past, most calculations based on nuclear forces have primarily focused on light nuclei only. In particular, there was no theory that could accurately describe the properties of heavier nuclei composed of dozens of nucleons due to the difficulties in computational simulations using supercomputers and the absence of precise theoretical models.
The new "Wave Function Matching” methodology aims to calculate the properties of even heavy atomic nuclei without approximation or parameter adjustments. This method utilizes the "Wave function" on a spacetime lattice and employs the "Monte Carlo method" for calculations, making it suitable for calculations on heavy nuclei, which were previously impractical due to the "Monte Carlo sign problem” arising in many-body systems.
To deal with the Monte Carlo sign problem, researchers initially determined the "two-body force” acting between two nucleons based on scattering experiments of protons and neutrons, and then applied the wave function matching method to transform it into a form suitable for calculations in quantum many-body systems. Additionally, they determined a "three-body force” nuclear model to explain the mass of nuclei containing three or more nucleons using the mass values of about 20 different nuclei. Through nuclear lattice calculations by applying the wave function matching methodology to both two-body and three-body forces, it was possible to derive theoretical calculations and predictions for various nuclei.
By applying the this methodology to nuclear lattice calculations, researchers have successfully predicted various properties of nuclei, from one-neutron one-proton nuclei (deuteron) to 58-nucleon nickel (Ni) nuclei. The binding energy, mass, and charge radius predicted using the method were found to be consistent with known experimental observations.
The collaboration effort went beyond just the physics community. The IBS researchers utilized the supercomputer Nurion at the Korea Institute of Science and Technology Information (KISTI) to calculate the binding energy of neutron-rich oxygen rare isotopes, up to oxygen-24 (24O).
This means that it is now possible to predict the exact properties of rare, exotic, and heavy nuclei before even making them. Currently, research is underway to apply nuclear lattice effective theory and wave function matching methods not only to nuclear structure but also to various other fields such as nuclear reactions.
Managing Director HONG Seung Woo of IRIS expressed optimism, stating, “We expect this research to be valuable for future studies on rare isotopes in South Korea using the RAON heavy ion accelerator.”
The research findings were published in the journal Nature. Reference Wavefunction matching for solving quantum many-body problems
Serdar Elhatisari, Lukas Bovermann, Yuan-Zhuo Ma, Evgeny Epelbaum, Dillon Frame, Fabian Hildenbrand, Myungkuk Kim, Youngman Kim, Hermann Krebs, Timo A. Lähde, Dean Lee, Ning Li, Bing-Nan Lu, Ulf-G. Meißner, Gautam Rupak, Shihang Shen, Young-Ho Song & Gianluca Stellin
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