Muon-Electron Hyperfine Coupling Constants of Muoniated Ethyl Radical: A Path Integral Simulation Study with Semiempirical Molecular Orbital Method

10.6122/CJP.52.126

Kenta Yamada；Yukio Kawashima；Masanori Tachikawa

Chinese Journal of Physics

52卷1期PartI（2014 / 02 / 01）

126 - 137

英文

We have investigated, by on-the-fly path integral molecular dynamics (PIMD) simulations, which can take into account the nuclear quantum and thermal effects, the nuclear quantum effect on the muoniated ethyl radical, where one of the hydrogen atoms of the methyl group in the ethyl radical is substituted with a muonium. Muonium consists of a positive muon and an electron, which can be considered as an ultra-light isotope of a hydrogen atom, and we here focused on the muon spin resonance/rotation/relaxation (μSR) and the hyperfine coupling constants (HFCC). Our PIMD simulation with the semiempirical PM6 method has succeeded in treating the nuclear quantum effect, which results mainly in the elongation of the bond length and the characteristic rotation of the CH2Mu group. Our PIMD simulation provides dramatic improvements in the characteristics of the HFCCs obtained from the conventional PM6 calculation, although the calculated HFCCs are not in qualitative agreement with the corresponding experimental ones because of the limitation of the semiempirical PM6 method for systems with an unpaired electron.