Freitag Leon, Lindenbauer Leopold, Oppel Markus, González Leticia
Institute of Theoretical Chemistry, Faculty of Chemistry, University of Vienna, Währinger Str. 17, 1090, Vienna, Austria.
Vienna Research Platform on Accelerating Photoreaction Discovery, University of Vienna, Währinger Str. 17, 1090, Vienna, Austria.
Chemphyschem. 2021 Nov 18;22(22):2371-2377. doi: 10.1002/cphc.202100549. Epub 2021 Oct 12.
A density matrix renormalization group-self consistent field (DMRG-SCF) study has been carried out to calculate the low-lying excited states of CpMo(CO) NO, a molybdenum complex containing NO and CO ligands. In order to automatically select an appropriate active space, a novel procedure employing the maximum single-orbital entropy for several states has been introduced and shown to be efficient and easy-to-implement when several electronic states are simultaneously considered. The analysis of the resulting natural transition orbitals and charge-transfer numbers shows that the lowest five excited electronic states are excitation into metal-NO antibonding orbitals, which offer the possibility for nitric oxide (NO) photorelease after excitation with visible light. Higher excited states are metal-centered excitations with contributions of metal-CO antibonding orbitals, which may serve as a gateway for carbon monoxide (CO) delivery. Time-dependent density functional theory calculations done for comparison, show that the state characters agree remarkably well with those from DMRG-SCF, while excitation energies are 0.4-1.0 eV red-shifted with respect to the DMRG-SCF ones.
已开展了一项密度矩阵重整化群自洽场（DMRG - SCF）研究，以计算CpMo(CO)NO（一种含有NO和CO配体的钼配合物）的低激发态。为了自动选择合适的活性空间，引入了一种对多个态采用最大单轨道熵的新方法，并且当同时考虑多个电子态时，该方法被证明是高效且易于实施的。对所得自然跃迁轨道和电荷转移数的分析表明，最低的五个激发电子态是激发到金属 - NO反键轨道，这为可见光激发后一氧化氮（NO）的光释放提供了可能性。更高的激发态是以金属为中心的激发，伴有金属 - CO反键轨道的贡献，这可能作为一氧化碳（CO）释放的途径。为作比较而进行的含时密度泛函理论计算表明，态特征与DMRG - SCF的结果非常吻合，而激发能相对于DMRG - SCF的结果有0.4 - 1.0 eV的红移。
