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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- 作者：T. Daniel Crawford ; Philip J. Stephens
- 刊名：Journal of Physical Chemistry A
- 出版年：2008
- 出版时间：February 14, 2008
- 年：2008
- 卷：112
- 期：6
- 页码：1339 - 1345
- 全文大小：89K
- 年卷期：v.112,no.6(February 14, 2008)
- ISSN：1520-5215
文摘
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 organicmolecules 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 comparablemagnitudes for all three methods. The origin-independent DFT and CC methods give the same sign of [
]Dfor every molecule except norbornanone. For every large-rotation ketone and alkene for which DFT and CCyield the incorrect sign as compared to liquid-phase experimental data, the corresponding optical rotatorydispersion (ORD) curve is bisignate, suggesting that the two models cannot reliably reproduce the relativeexcitation energies and antagonistic rotational strengths of multiple competing electronic states that contributeto the total long-wavelength rotation. Several potential sources of error in the theoretical treatments areconsidered, including basis set incompleteness, vibrational and temperature effects, electron correlation, andsolvent effects.
]Dfor every molecule except norbornanone. For every large-rotation ketone and alkene for which DFT and CCyield the incorrect sign as compared to liquid-phase experimental data, the corresponding optical rotatorydispersion (ORD) curve is bisignate, suggesting that the two models cannot reliably reproduce the relativeexcitation energies and antagonistic rotational strengths of multiple competing electronic states that contributeto the total long-wavelength rotation. Several potential sources of error in the theoretical treatments areconsidered, including basis set incompleteness, vibrational and temperature effects, electron correlation, andsolvent effects.