The structural, electronic, and optical properties of NpO2 and PuO2: a hybrid density-functional-theory studyShi-Chang Li, Yong Guo, Tao Gao and Bing-Yun AoEur. Phys. J. B, 88 9 (2015) 230DOI: https://doi.org/10.1140/epjb/e2015-50681-9