Structure and Stability of Tube and Cage Ge<sub>60</sub>H<sub>60</sub>

A tube Ge<sub>60</sub>H<sub>60</sub> isomer in <i>D</i><sub>5<i>d</i></sub> symmetry with fused five-membered rings located at the ends of the tube is more stable than the fullerene-like <i>I</i><sub><i>h</i></sub> cage isomer at the B3LYP/cc-pVDZ level of theory. Introducing endo Ge−H bonds increases the stability of both cage and tube isomers. The most stable tube isomer can admit six endo Ge−H bonds. The cage isomer can admit 10−12 endo Ge−H bonds (H<sub>10</sub>@Ge<sub>60</sub>H<sub>50</sub> and H<sub>12</sub>@Ge<sub>60</sub>H<sub>48</sub>), and they also represent the most stable Ge<sub>60</sub>H<sub>60</sub> isomers. The stability order and structural patterns of Ge<sub>60</sub>H<sub>60</sub> are the same as those found for the corresponding Si<sub>60</sub>H<sub>60</sub> isomers. Moreover, it is found that the 6-31G(d,p) basis set fails to predict the relative energies of the Ge<sub>60</sub>H<sub>60</sub> isomers and the Ge<sub>6</sub>H<sub>6</sub> isomers.