University of Regensburg, Institute of Inorganic Chemistry, Universitätsstr. 31, 93040 Regensburg, Germany.
J Chem Phys. 2013 Dec 7;139(21):214705. doi: 10.1063/1.4832698.
In the course of the recent advances in chemical structure prediction, a straightforward type of diagram to evaluate phase stabilities is presented based on an expedient example. Crystal structures and energetic stabilities of dipnictides NiPn2 (Pn = N, P, As, Sb, Bi) are systematically investigated by first principles calculations within the framework of density functional theory using the generalized gradient approximation to treat exchange and correlation. These dipnictides show remarkable polymorphism that is not yet understood systematically and offers room for the discovery of new phases. Relationships between the concerned structures including the marcasite, the pyrite, the arsenopyrite/CoSb2, and the NiAs2 types are highlighted by means of common structural fragments. Electronic stabilities of experimentally known and related AB2 structure types are presented graphically in so-called stability diagrams. Additionally, competing binary phases are taken into consideration in the diagrams to evaluate the stabilities of the title compounds with respect to decomposition. The main purpose of the stability diagrams is the introduction of an image that enables the estimation of phase stabilities at a single glance. Beyond that, some of the energetically favored structure types can be identified as potential new phases.
在化学结构预测的最新进展中，本文基于一个简单的示例，提出了一种用于评估相稳定性的直观图表。通过第一性原理计算，在密度泛函理论框架内，利用广义梯度近似处理交换关联，系统研究了二主族元素化合物 NiPn2（Pn = N、P、As、Sb、Bi）的晶体结构和能量稳定性。这些二主族元素化合物表现出显著的多晶型性，这种多晶型性尚未得到系统的理解，为发现新相提供了空间。通过常见的结构片段，突出了所研究结构之间的关系，包括辉铁矿、黄铁矿、砷黝铜矿/CoSb2 和 NiAs2 型。通过所谓的稳定性图，以图形方式呈现了实验已知和相关 AB2 结构类型的电子稳定性。此外，在这些图中还考虑了竞争二元相，以评估标题化合物相对于分解的稳定性。稳定性图的主要目的是引入一个图像，使人们能够在一眼就能估计相稳定性。除此之外，一些能量上有利的结构类型可以被确定为潜在的新相。
