QTAIM and the stress tensor were used to provide a detailed analysis of the topology of the molecular graph, BCP and bond-path properties, including the new introduced helicity length H, of a Tyr-Gly dipeptide conformer subjected to a torsion with four levels of theory; MP2, M06-2X, B3LYP-D3 and B3LYP and a modest-sized basis set, 6-31+G(d).

Structural effects and bonding properties are quantified and reflect differences in the BSSE and lack of inclusion of dispersion effects in the B3LYP calculations. The helicity length H demonstrated that MP2 produced a unique response to the torsion suggesting future use as a diagnostic tool.

中文翻译：

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用QTAIM的新工具和二肽构象体的应力张量评估理论水平选择的后果。

QTAIM和应力张量用于提供分子图拓扑，BCP和键路径特性的详细分析，包括新引入的Tyr-Gly二肽构象异构体的螺旋长度H，受到四个水平的扭转理论; MP2，M06-2X，B3LYP-D3和B3LYP以及中等大小的基本集6-31 + G（d）。

量化了结构效应和键合特性，并反映了BSSE中的差异以及B3LYP计算中没有包含色散效应。螺旋长度H证明MP2对扭力产生了独特的响应，表明将来可作为诊断工具使用。