Relaxed atomic structure and room-temperature transport coefficients and ZT of ZnO NWs. (a), (b), and (c) shows the  cross section of 8-, 10-, and 17-Å-diameter NWs, respectively. Grey spheres denote Zn atoms and red spheres indicate O atoms. (d) shows the side view of 8-Å-diameter NW. In the transport coefficients plots, the red, blue, and green lines denote the results for NW of diameter 8, 10, and 17 Å, respectively. The bulk values (black dashed lines) are shown for comparison. (Color online).