On the applicability of time-dependent density functional theory (TDDFT) and semiempirical methods to the computation of excited-state potential energy surfaces of perylene-based dye-aggregates

详细信息    查看全文

• 作者：Christof Walter ; Veronika Krä ; mer and Bernd Engels
• 刊名：International Journal of Quantum Chemistry
• 出版年：2017
• 出版时间：March 15, 2017
• 年：2017
• 卷：117
• 期：6
• 全文大小：2048K
• ISSN：1097-461X

文摘

The excited states of perylene-based dye aggregates were investigated with emphasis on the description of the potential energy surfaces for the intermolecular motion in a dimer, which are of importance for exciton trapping. The aim is to investigate the applicability of TDDFT and semiempirical methods. The longitudinal displacement of two π-stacked molecules against each other is used as model and the methods are benchmarked against SCS-CC2 and SCS-ADC(2). Furthermore a simple character analysis is applied. In the case of the perylene dimer, CAM-B3LYP and ωB97XD provide accurate results. However, while CAM-B3LYP fails for the PBI (perylene bisimide) dimer the performance of ωB97XD is highly dependent on the used monomer geometry due to close-lying diabatic states. A change in geometry changes the character of the excited states even qualitatively. The accuracy of several other long-range corrected functionals (LC-BLYP, LC-ωPBE, ωB97X) and the effect of empirically tuning the range-separation parameter of ωB97XD are also presented for this interesting case. Furthermore, it is shown that the semiempirical method OM2 fails to provide a correct description of the excited states when the orbital overlap plays a significant role. This is attributed to the too contracted basis set.