A Density Functional Theory (DFT) study of the electronic, energetic, dynamical, and mechanical properties of new glycine molecular crystals is presented here. Our search of the potential energy surface (PES) reproduces the previously reported structures for $\alpha$–, $\beta$–, and $\gamma$–glycine with $P{2}_{1/n},P{2}_1,P{3}_1$ symmetries, respectively. In addition, we report three new orthorhombic (o), tetragonal (t), and monoclinic (m) crystals with $P{2}_1{2}_1{2}_1,P{4}_3$, and $P{2}_1$ symmetries. The crystals have wide band gaps, classifying them in the range of insulators. All three new phases have low mechanical hardness (< 3.2 GPa), characterizing them as soft crystals. Topological and local energetic properties of the electronic densities for the new crystalline phases of glycine have been calculated using the tools provided by the quantum theory of atoms in molecules (QTAIM) under periodic conditions. Typical NH$\cdots$O, OH$\cdots$O as well as secondary CH$\cdots$O hydrogen bonds (HBs), act as the stabilizing factors resulting in large cohesive energies for the new phases of glycine crystals. Without exception, all types of HBs, for all new phases, perfectly fit the attractive region of a Lennard–Jones potential.

本文介绍了对新甘氨酸分子晶体的电子，能量，动力学和机械特性的密度泛函理论（DFT）研究。我们对势能面（PES）的搜索再现了先前报道的结构$\alpha$– $\beta$-， 和 $\gamma$–甘氨酸与 $P{\mathrm{2个}}_{\mathrm{1个}/ñ}，P{\mathrm{2个}}_{\mathrm{1个}}，P{3}_{\mathrm{1个}}$对称。此外，我们报告了三种新的正交晶体（o），四方晶体（t）和单斜晶体（m）晶体，$P{\mathrm{2个}}_{\mathrm{1个}}{\mathrm{2个}}_{\mathrm{1个}}{\mathrm{2个}}_{\mathrm{1个}}，P{4}_3$， 和 $P{\mathrm{2个}}_{\mathrm{1个}}$对称性。晶体具有宽带隙，将它们分类为绝缘体的范围。这三个新相均具有较低的机械硬度（<3.2 GPa），将其表征为软晶体。甘氨酸新晶相的电子密度的拓扑和局部高能性质已使用周期性的分子中原子的量子理论（QTAIM）提供的工具进行了计算。典型NH$\cdots$O，OH$\cdots$O以及次要CH$\cdots$O氢键（HBs）充当稳定因子，导致甘氨酸晶体新相具有较大的内聚能。无一例外，所有新阶段的所有类型的HBs都完美契合了Lennard-Jones潜力的诱人区域。