The influence of pressure on structural, electronic, and optical properties of choline iodide is studied within the density functional theory approach using the РВЕ gradient functional, the D3(BJ) dispersion correction, and a basis set of localized orbitals. Elastic constants, parameters of the Birch–Murnaghan equation of state, density of electronic states, and frequencies of normal longwave vibrations are calculated. It is shown that the immediate environment of the iodine atom contains 12 carbon atoms with the shortest O–H⋯I distance equal to 2.486 Å. The О–H distance increases slightly together with pressure, and the I–H distance decreases while its linear modulus is an order of magnitude smaller than the bulk modulus under 97 GPa. In contrast to intramolecular vibrations, the pressure shifts of lattice vibrations exceed 10 cm–1/GPa, and their modal Grüneisen parameters are an order of magnitude larger.

中文翻译：

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压力对碘化胆碱的结构、电子和光学性质的影响

在密度泛函理论方法中，使用 РВЕ 梯度泛函、D3(BJ) 色散校正和局部轨道基组，研究了压力对碘化胆碱的结构、电子和光学性质的影响。计算弹性常数、Birch-Murnaghan 状态方程的参数、电子态密度和正常长波振动的频率。结果表明，碘原子的直接环境包含 12 个碳原子，最短的 O–H⋯I 距离等于 2.486 Å。О-H 距离随着压力的增加而略有增加，I-H 距离减小，但在 97 GPa 下其线性模量比体积模量小一个数量级。与分子内振动相反，晶格振动的压力位移超过 10 cm-1/GPa，