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首页> 外文期刊>The journal of physical chemistry, A. Molecules, spectroscopy, kinetics, environment, & general theory >Comparison of time-dependent density-functional theory and coupled cluster theory for the calculation of the optical rotations of chiral molecules
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Comparison of time-dependent density-functional theory and coupled cluster theory for the calculation of the optical rotations of chiral molecules

机译：时变密度泛函理论和耦合簇理论在手性分子旋光度计算中的比较

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摘要

A comparison of the abilities of time-dependent density-functional theory (TDDFT) and coupled cluster (CC) theory to reproduce experimental sodium D-line specific rotations for 13 conformationally rigid organic molecules is reported. The test set includes alkanes, alkenes, and ketones with known absolute configurations. TDDFT calculations make use of gauge-including atomic orbitals and give origin-independent specific rotations. CC rotations are computed using both the origin-independent dipole-velocity and origin-dependent dipole-length representations. The mean absolute deviations of calculated and experimental rotations are of comparable magnitudes for all three methods. The origin-independent DFT and CC methods give the same sign of [alpha]D for every molecule except norbornanone. For every large-rotation ketone and alkene for which DFT and CC yield the incorrect sign as compared to liquid-phase experimental data, the corresponding optical rotatory dispersion (ORD) curve is bisignate, suggesting that the two models cannot reliably reproduce the relative excitation energies and antagonistic rotational strengths of multiple competing electronic states that contribute to the total long-wavelength rotation. Several potential sources of error in the theoretical treatments are considered, including basis set incompleteness, vibrational and temperature effects, electron correlation, and solvent effects.
机译：报告了时间依赖性密度泛函理论（TDDFT）和耦合簇（CC）理论再现13种构象刚性有机分子的钠D线比旋光实验能力的比较。测试装置包括具有已知绝对构型的烷烃，烯烃和酮。 TDDFT计算利用包括轨距在内的原子轨道，并给出与原点无关的特定旋转。使用与原点无关的偶极速度和与原点相关的偶极长度表示法来计算CC旋转。对于这三种方法，计算和实验旋转的平均绝对偏差都具有可比较的大小。除降冰片酮以外的每个分子的不依赖原点的DFT和CC方法给出相同的αD符号。对于DFT和CC与液相实验数据相比其符号均不正确的每一个大旋转的酮和烯烃，相应的旋光色散（ORD）曲线都是双正态的，这表明这两个模型无法可靠地再现相对激发能和多种竞争电子态的对抗旋转强度，这些竞争态有助于总长波长旋转。考虑了理论处理中的几种潜在错误源，包括基集不完整，振动和温度效应，电子相关性和溶剂效应。

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