Quantum-chemical prediction and computational characterization of high-pressure transitionmetal nitrides and oxynitrides

这个理论项目的目的是预测，通过各种量子化学技术，存在一些新的氮化物和氮氧化物的化合物，这些化合物只能通过使用极端的合成压力而不是使用普通的实验方法来获得。我们将通过利用一些从头计算策略来实现这一目标，我们将与Rainer Niewa（MPI Dresden，很快TU München）和Ulrich施瓦茨（MPI Dresden）的实验工作组密切互动。特别是，我们将进行总能量计算的假设和化学计量合理的过渡金属氮化物和氮氧化物，我们将计算分析其热化学稳定性相对于竞争（离析物）相合成前，即通过模拟他们的高压行为在不同的压力高达100 GPa的形式从头能量<$体积和焓<$压力图。这提供了理论上的相变压力，甚至提供了所有反应物都是固态材料的地层压力。参数温度将使用简单的近似值引入，从而产生压力温度图，这将使我们的实验伙伴能够轻松地提取最佳合成压力和温度范围，即使涉及气态反应物。特别是，我们将从理论上预测潜在稳定的二元过渡金属/铂族氮化物，四元氮化物（M，M与M是铬，锰和铁。最终，我们将协助我们的合成合作伙伴识别和分析他们的合成材料，包括发现的结构类型，原子位置参数，原子分布，物理性质预测，特别是通过DOS和COHP分析的键合情况。

The purpose of this theoretical project is to predict, by means of various quantum-chemical techniques, the existence of a number of novel nitridic and also oxynitridic compounds which are only accessible by using extreme synthetic pressures but not using ordinary experimental methods. We will accomplish this goal by utilizing a number of ab initio computational strategies, and we will closely interact with the experimentally working groups of Rainer Niewa (MPI Dresden, soon TU München) and Ulrich Schwarz (MPI Dresden). In particular, we will perform total-energy calculations for hypothetical and stoichiometrically reasonable transition-metal nitrides and oxynitrides, and we will computationally analyze their thermochemical stabilities with respect to competing (educt) phases prior to synthesis, namely by simulating their high-pressure behavior at different pressures up to 100 GPa in the form of ab initio energy¿volume and enthalpy¿pressure diagrams. This gives access to theoretical phase-transition pressures and even to formation pressures provided that all reactants are solid-state materials. The parameter temperature will be introduced using a simple approximation, thereby yielding pressure¿temperature diagrams which will allow our experimental partners to easily extract the optimum synthetic pressures and temperature ranges even if gaseous reactants should be involved. In particular, we will theoretically predict potentially stable binary transition-metal/platinum-group nitrides, quaternary nitrides (M,M¿)Fe3N incorporating different iron- and platinum-group metals, as well as daltonide and berthollide oxynitrides ¿MON¿ with M being chromium, manganese, and iron. Eventually, we will assist our synthetic partners in identifying and analyzing their synthesized materials with respect to the structure type found, atomic-site parameters, atomic distributions, prediction of physical properties and, especially, the bonding situation via DOS and COHP analyses.