Lehrstuhl für Theoretische Physik, Universität Paderborn, 33095 Paderborn, Germany.
Phys Rev Lett. 2010 Sep 17;105(12):126102. doi: 10.1103/PhysRevLett.105.126102.
Density functional theory calculations are performed to determine the mechanism and origin of the intensively debated (4 x 1)-(8 x 2) phase transition of the Si(111)-In nanowire array. The calculations (i) show the existence of soft phonon modes that transform the nanowire structure between the metallic In zigzag chains of the room-temperature phase and the insulating In hexagons formed at low temperature and (ii) demonstrate that the subtle balance between the energy lowering due to the hexagon formation and the larger vibrational entropy of the zigzag chains causes the phase transition.
采用密度泛函理论计算方法确定了 Si(111)-In 纳米线阵列中备受争议的（4 x 1）-(8 x 2)相转变的机制和起源。计算结果表明：（i）存在软声子模式，这种模式可以在室温相的金属 In 之字形链和低温下形成的绝缘 In 六边形之间转换纳米线结构；（ii）证明了由于六边形的形成而导致的能量降低与之字形链的较大振动熵之间的微妙平衡导致了相变。
