New Physics: Sae Mulli

Aims and Scope

The origin of New Physics: Sae Mulli (NPSM, ISO abbreviation: New Phys.: Sae Mulli.): Sae Mulli (새물리 in Korean characters means ‘new physics’) is the oldest Korean pure scientific journal. It was first published in 1961 just after the Korean War by the Korean Physical Society (KPS). The primary mission of Sae Mulli was to start building up Korean physics research community from almost nothing and in fact Sae Mulli had made tremendous contributions to the Korean science community. Through a peer-review system, Sae Mulli had continued elevating the level of scientific researches, consequently becoming a cornerstone of the economic miracle of Korea...

Editor-in-Chief : Sunglae CHO
New Physics: Sae Mulli Editorial Board

pISSN : 0374-4914
eISSN : 2289-0041

Tel : +82-2-556-4737
Fax : +82-2-554-1643
E-mail: npsm@npsm-kps.org

Research Papers

Magnetic Resonance Study of $^{7}$Li and $^{39}$K Nuclei in Li$_{3}$K(SO$_{4}$)$_{2}$ Single Crystals

Tae Ho YEOM*

Department of Laser and Optical Information Engineering, Cheongju University, Cheongju 28503, Korea

Li$_{3}$K(SO$_{4}$)$_{2}$ single crystals were grown and the lattice constants were determined by using X-ray diffraction. The nuclear magnetic resonances (NMR) in the $^{7}$Li and the $^{39}$K nucleus in Li$_{3}$K(SO$_{4}$)$_{2}$ single crystals were investigated by using Fourier transform NMR (FT-NMR) spectrometry. The quadrupole interaction of $^{7}$Li nuclei decreases as the temperature is increased. $T_{1}$, the spin-lattice relaxation time, for $^{7}$Li and $^{39}$K in Li$_{3}$K(SO$_{4}$)$_{2}$ crystal was analyzed in the temperature range of 180 K -- 430 K. The $T_{1}$ values for the $^{7}$Li and the $^{39}$K nuclei in the crystals decrease linearly as temperature is increased. The mechanism of the spin-lattice relaxation for both the $^{7}$Li and the $^{39}$K nuclei in Li$_{3}$K(SO$_{4}$)$_{2}$ single crystals seems to be a single-phonon direct process, not a Raman process. $E_{a}$, the activation energies for the molecular motions of the $^{7}$Li and the $^{39}$K nuclei surrounded by oxygen atoms were found to be 3.08 $\pm$ 0.19 kJ/mol ($\omega_{0}$/2$\pi$ = 77.27 MHz) and 2.52 $\pm$ 0.19 kJ/mol ($\omega_{0}$/2$\pi$ = 155.51 MHz) for $^{7}$Li nucleus and 1.36 $\pm$ 0.08 kJ/mol (18.67 MHz) for the $^{39}$K nucleus.

New Phys.: Sae Mulli 2020; 70: 405-411

Calculation Method of Total Energy and Atomic Interaction Potential Through Machine Learing Using a Neural Network of Atomic Structure Data

Doukyun KIM¹, Chul Hong PARK²*

¹Department of Physics, Pusan National University, Pusan 46241, Korea

²Department of Physics Education, Pusan National University, Pusan 46241, Korea

We examined a machine learning method to extract the atom-pair interaction potential energy in materials. The data for the atomic structures and the corresponding total energies were generated by using the ab-initio molecular dynamic simulation, by which the artificial neural network (ANN) was trained to predict the total energies of the materials. Two ANNs were assigned: one to simulate (i) the dependence of the atom-pair interaction energy on the distance between the nearest atoms and the other to simulate (ii) the angular distortion energy. We found that compared to the true energies the total energies of Si could be successfully predicted with an error of about 1 meV/atom for atomic structures generated at 300 K, and that the dependence of the atomic interaction energy on the distance and the angular distortion energy could be obtained by training an ANN for atomic structures of various volumes.

New Phys.: Sae Mulli 2020; 70: 398-404