The stiffness tensor and elastic anisotropy characteristics for the crystalline hydrogen maleates of l-isoleucinium, l-leucinium, and l-norvalinium with l-norvaline have been calculated using the periodic DFT calculations and atom-centered basis sets. The H-bond orientations have been compared with spatial directions of the minimum and maximum values of Young’s modulus, shear modulus, and linear compressibility. In spite of the similar layered structures, l-isoleucinium and l-leucinium hydrogen maleates show significant difference in elastic moduli anisotropy. The flexibility of l-leucinium hydrogen maleate is explained by the relatively high universal elastic anisotropy index and the large anisotropy ratios of elastic moduli. In its turn, this index is determined by the almost coincidental Young’s modulus maximum direction and the orientation of the strongest H-bonds.

中文翻译：

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H键布局如何确定结晶性氨基酸马来酸氢盐的机械性能

刚性张量和结晶氢马来酸酯的弹性各向异性特性升-isoleucinium，升-leucinium，和升与-norvalinium升-norvaline已经使用周期DFT计算和原子为中心的基组计算。已经将H键取向与杨氏模量，剪切模量和线性可压缩性的最小值和最大值的空间方向进行了比较。尽管层状结构相似，但是1-异亮氨酸和1-亮氨酸马来酸氢盐在弹性模量各向异性上显示出显着差异。l的灵活性-马来酸亮氨酸锂的解释是相对较高的通用弹性各向异性指数和较大的弹性模量各向异性比。反过来，该指数由几乎重合的杨氏模量最大方向和最强的H键的方向确定。