首页> 外文期刊>The journal of physical chemistry, A. Molecules, spectroscopy, kinetics, environment, & general theory >Density functional theory study of the properties of N-H center dot center dot center dot N, noncooperativities, and intermolecular interactions in linear trans-diazene clusters up to ten molecules
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Density functional theory study of the properties of N-H center dot center dot center dot N, noncooperativities, and intermolecular interactions in linear trans-diazene clusters up to ten molecules

机译:密度泛函理论研究最多10个分子的线性反式二氮烯簇中N-H中心点的性质,非合作性和分子间的相互作用

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We investigate aspects of N-H center dot center dot center dot N hydrogen bonding in the linear trans-diazene clusters (n = 2-10) such as the N center dot center dot center dot H and N-H lengths, n(N) -> sigma*(N-H) interactions, N center dot center dot center dot H strengths, and frequencies of the N-H stretching vibrations utilizing the DFT/B3LYP theory, the natural bond orbital (NBO) method, and the theory of atoms in molecules ( AIM). Our calculations indicate that the structure and energetics are qualitatively different from the conventional H-bonded systems, which usually exhibit distinct cooperative effects, as cluster size increases. First, a shortening rather than lengthening of the N-H bond is found and thus a blue rather than red shift is predicted. Second, for the title clusters, any sizable cooperative changes in the N-H and N center dot center dot center dot H lengths, n(N) -> sigma*(N-H) charge transfers, N center dot center dot center dot H strengths, and frequencies of the N-H stretching vibrations for the linear H-bonded trans-diazene clusters do not exist. Because the n(N) -> sigma*(N-H) interaction hardly exhibits cooperative effects, the capability of the linear trans- diazene cluster to localize electrons at the N center dot center dot center dot H bond critical point is almost independent of cluster size and thereby leads to the noncooperative changes in the N center dot center dot center dot H lengths and strengths and the N-H stretching frequencies. Third, the dispersion energy is sizable and important; more than 30% of short-range dispersion energy not being reproduced by the DFT leads to the underestimation of the interaction energies by DFT/B3LYP. The calculated nonadditive interaction energies show that, unlike the conventional H- boned systems, the trans-diazene clusters indeed exhibit very weak nonadditive interactions.
机译:我们研究了线性反二烯簇(n = 2-10)中NH中心点中心点中心点N氢键的各个方面,例如N中心点中心点中心点H和NH长度,n(N)-> sigma *(NH)相互作用,N个中心点中心点中心点H强度以及使用DFT / B3LYP理论,自然键轨道(NBO)方法和分子中原子理论(AIM)的NH拉伸振动的频率。我们的计算表明,结构和能量学性质与常规的H键系统不同,后者随着簇尺寸的增加通常表现出明显的协同作用。首先,发现了N-H键的缩短而不是延长,因此预测了蓝移而不是红移。其次,对于标题簇,NH和N个中心点中心点中心点H长度,n(N)-> sigma *(NH)电荷转移,N个中心点中心点中心点H强度以及线性氢键连接的跨二烯簇的NH伸缩振动频率不存在。由于n(N)-> sigma *(NH)的相互作用几乎不表现出协同效应,因此线性反式二氮烯簇将电子定位在N中心点中心点中心点H键临界点的能力几乎与簇大小无关从而导致N中心点中心点中心点H的长度和强度以及NH拉伸频率的不合作变化。第三,分散能相当重要。 DFT无法复制超过30%的短程分散能,这会导致DFT / B3LYP的相互作用能被低估。计算得出的非加性相互作用能表明,与常规的H-骨体系不同,反式二氮烯簇确实表现出非常弱的非加性相互作用。

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