Max Planck Institute for Solid State Research, Heisenbergstr. 1, D-70569 Stuttgart, Germany.
J Phys Chem B. 2010 Dec 2;114(47):15573-81. doi: 10.1021/jp1028504. Epub 2010 Nov 5.
The enthalpy landscape of CaC(2) was investigated on the ab initio level, and possible (meta)stable structures are predicted. Simulated annealing was used as a global exploration method for the determination of the local minima on the enthalpy landscapes, where the only information supplied was the number of atoms per unit cell. Subsequently, the structure candidates found were locally optimized. At all stages of the search, the energy calculations were performed on the ab initio level. Furthermore, we investigated the enthalpies of different modifications as a function of pressure, and we found that, at a transition pressure of about 30 GPa, CaC(2) should transform from a 6-fold coordinated structure resembling a rock-salt structure to an 8-fold coordinated one similar to the CsCl structure. At standard pressure, two new energetically low-lying (metastable) structures were found, and at high pressure an additional new metastable structure was also predicted to be capable of existence.
我们在从头算水平上研究了碳化钙的焓景观，并预测了可能的（亚稳）稳定结构。我们使用模拟退火作为全局探索方法，以确定焓景观上的局部最小值，其中仅提供了单位晶胞中的原子数这一信息。随后，我们对找到的结构候选物进行了局部优化。在搜索的所有阶段，能量计算都是在从头算水平上进行的。此外，我们还研究了不同变体的焓随压力的变化，发现碳化钙在约 30 GPa 的相变压力下，应该从类似于岩盐结构的六配位结构转变为类似于 CsCl 结构的八配位结构。在标准压力下，我们发现了两种新的能量较低的（亚稳）结构，而在高压下，还预测到另一种新的亚稳结构也有可能存在。
