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

这个理论项目的目的是通过各种量子化学技术来预测一些新的氮化物和氧氮化合物的存在，这些化合物只能通过极端的合成压力才能获得，而不是使用普通的实验方法。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，Soon TU München)和Ulrich Schwarz(MPI Dresden)的实验工作组密切互动。特别是，我们将对假设的和化学计量合理的过渡金属氮化物和氧氮化物进行总能量计算，并将计算分析它们在合成之前相对于竞争(排出)相的热化学稳定性，即以从头算能量体积和焓压力图的形式模拟它们在高达100 Gpa的不同压力下的高压行为。在所有反应物都是固态材料的情况下，这提供了理论相变压力甚至形成压力的途径。参数温度将使用一个简单的近似值来引入，从而产生压力温度图，该图将允许我们的实验合作伙伴轻松地提取最佳合成压力和温度范围，即使应该涉及气态反应物。特别是，我们将在理论上预测潜在稳定的二元过渡金属/铂族氮化物、含有不同铁族金属和铂族金属的季氮化物(M，M)Fe3N，以及具有M为铬、锰和铁的达托尼德和贝索洛里德氧化物氮化物。最终，我们将通过DOS和COHP分析，帮助我们的合成伙伴识别和分析他们的合成材料，包括所发现的结构类型、原子位置参数、原子分布、物理性质的预测，特别是成键情况。

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.