We systematically investigate the crystal structure of Ba-doped phenanthrene with various Ba doping levels by the first principle calculation method combining with the X-ray diffraction (XRD) spectra simulation. The optimized lattice parameters and the simulated XRD spectra of Ba2phenanthrene are in good agreement with the experiment ones, and the strength difference of a few of XRD peaks can be explained by the existence of undoped phenanthrene in the experimental sample. Although the stoichiometry ratio of Ba atom and phenanthrene molecule is 1.5:1, the simulated XRD spectra, space group symmetry and the optimized lattice parameters of Ba1.5phenanthrene are not consistent to the measured values. The sample of Ba-doped phenanthrene is deduced to be the mixture of Ba2phenanthrene and some amount of undoped phenanthrene, instead of uniform Ba1.5phenanthrene. Our calculations indicate that Ba2phenanthrene is a semiconductor with a small energy gap less than 0.05 eV. Our findings provide the fundamental information of crystal structure and electronic properties of Ba-doped phenanthrene superconductor.
@article{arxiv.1403.1190,
title = {Ba$_2$phenanthrene is the main component in the Ba-doped phenanthrene sample},
author = {Xun-Wang Yan and Zhongbing Huang and Hai-Qing Lin},
journal= {arXiv preprint arXiv:1403.1190},
year = {2014}
}